Immigrant Niches and Immigrant Networks in the U.S. Labor Market

Immigrants come to the United States to work and to improve their earnings and material living conditions, and in doing so, they often drive economic growth and local revitalization. Their labor market involvement may either supplement or displace employment opportunities for native-born populations, and immigrant groups can vary significantly in the economic success they achieve in this country. The consensus among economists who assess the macro effects of economic activity and among sociologists who address the impact of non-economic forces on economic activity is that, on balance, the U.S. national economy—as well as immigrants themselves—benefit from their labor market contributions.¹

The essays in this issue deepen our understanding of different labor market experiences of immigrant groups by drawing on the expertise and insight not only of economists and sociologists but also of demographers, geographers, and anthropologists who value interdisciplinary scholarship. Drawing on somewhat different but overlapping frames and methods of analyses, these essays enhance our understanding of the labor market experiences of new immigrants and of the opportunities and constraints they face in the economic niches in which they obtain work. The qualitative scholars contribute insight into the distinctive features and dynamics of different occupational niches that quantitative analyses fail to capture. At the same time, quantitative scholars elucidate the broad trends and regularities in labor market activity that are missed by case studies. Few quantitative sociologists talk of "niches," and virtually no economist does. They instead focus on "labor markets"—considered as broad aggregates of workers and firms—and on wage effects and wage differentials across immigrant groups and between immigrants and U.S.-born workers. Yet quantitative social scientists have come to recognize the large heterogeneity of skills in the native and immigrant populations and to understand that specific labor market involvements are also shaped by institutions and informal social dynamics.

Our own research spans these two approaches. Likewise, our goal in this volume is to combine the insights that scholars of different disciplines, making use of different methodologies, contribute to our understanding of immigrant labor market involvements. Giovanni Peri, a quantitative economist, has devoted much of his research to enriching the quantitative analysis of the labor market effects of immigrants by incorporating the important building blocks of immigrants' skill specificity, their complementarity to native-born skills, and the heterogeneity of their experiences into the quantitative models used to analyze immigrants in labor markets and understand their effects.² Susan Eckstein, a qualitative historical sociologist, has enhanced our understanding of immigrant and native-born labor market experiences by demonstrating that immigrant labor market experiences may be transnationally embedded in both the supply of labor for distinctive "niches" and the evolution of U.S.-formed immigrant niches. Her work highlights how immigrants do not merely respond to preexisting demand for particular labor but sometimes create demand for their labor. In other words, across the skill spectrum, they may construct new markets.

In combining the expertise of the scholars of diverse social science disciplines represented in this volume with our own respective areas of expertise, we hope to "open the box" of immigrant labor market dynamics with new synergy and insight into new immigrant labor market experiences. Simple quantitative statistics, case studies, and more sophisticated regression analyses are used together in this volume to highlight the "value added" of examining new immigrant labor market experiences from different analytic perspectives associated with different social science disciplines and different methods of analysis.

As coeditors of this volume, we begin here by describing first the characteristics of niches and then the occupational niches in which today's foreign-born workers cluster and are overrepresented relative to their percentage of U.S. employment. We then address the specific labor market sectors in which the main immigrant groups work. We explain the dependence of niching on demand for their skills, their abilities, and, more generally, their individual characteristics. Once an immigrant group gets a footing in a particular line of economic activity, in-group social networks and informal dynamics contribute to that group's continued association with the niche. Immigration and labor policies and institutional practices may also contribute, intentionally or not, to the ongoing involvement of particular immigrant groups in certain labor market niches. These forces impede unfettered market forces from determining who does what work, but in ways that may enhance economic production and productivity by inducing worker loyalty, commitments, and investments.

THE FORMATION OF IMMIGRANT NICHES

Many immigrants are concentrated in an occupation, or a segment of an occupation, that we call a "labor market niche": a specific line of work found either within a single community or nationwide. A specific line of work represents an "immigrant niche" if an immigrant group is overrepresented in it relative to the group's portion of the country's employment. Some occupations are dominated by immigrants in general; in other cases, specific immigrant groups are associated with specific labor market niches.³ Some heavily "niched" immigrant groups come from particular regions of a country or from specific ethnic groups in a country. Armenians from Syria and Persian Jews, for instance, dominate specific retail store sectors; Indians from the state of Punjab are highly concentrated as employees of gas stations, while Indians from the state of Gujarat mainly work in the hotel and motel business (Dhingra 2012).

Immigrant niching is not new. Historically, distinctive groups of immigrants engaged in distinctive work. Niching was already taking place in the nineteenth and early twentieth centuries, as documented by several historical accounts of the Chinese (for example, Kwong and Miščević 2005) and other groups. Siobhan O'Keefe and Sarah Quincey (this issue) illustrate one of these historical examples. The authors detail how a large wave of Russian Jews was encouraged to settle in rural New Jersey and to engage in farming during the last decades of the nineteenth century. This was a somewhat special case in that these colonies were partially supported by Jewish philanthropists to divert the large flow of Russian Jews away from the cities where Jews had settled earlier, but the dynamic they produced in rural New Jersey was rather typical. As O'Keefe and Quincy show, the immigrants' arrival revitalized local markets, reducing natives' out-migration because of new opportunities to sell to and work for the new settlers. However, their presence increased the unemployment of local workers in similar jobs. Zai Liang and Bo Zhou (this issue), in turn, trace the occupational niches involving Chinese immigrants in the late nineteenth century that became the basis for Chinese immigrant niches and niche diversification in the last thirty years.

The main focus of this volume is on the features and dynamics of labor market niches that employ contemporary immigrants, commonly referred to as "new immigrants." We address the formation, perpetuation, and, in some instances, transformation and transnationalization of today's niches by the interplay of social and economic dynamics that sociology and economics—and secondarily other social sciences—can help us understand.

Even as labor market niching provides opportunities for immigrants, a group's successful occupation of a niche often closes opportunities for nongroup members. Sometimes tensions arise—or at least difficult coexistence—from the displacement of local workers or previous immigrant groups.⁴ Tod G. Hamilton, Janeria A. Easley, and Angela R. Dixon (this issue) analyze whether the lower degree of niching in the U.S.-born African American community, documented using census data, is a determinant of their wage disadvantage relative to foreign-born blacks. While African- and Caribbean-born blacks tend to be more concentrated in specific niches than native blacks, the authors do not find this to be a significant determinant of their wage advantage.

CONTEMPORARY IMMIGRANT NICHES

The national origins of U.S. immigrants changed markedly in the last half-century; at the same time, the foreign-born share of the U.S. population reached levels not experienced since the 1920s, with record levels in absolute numbers. In this introduction, we focus (with the exception of the O'Keefe and Quincy essay) on immigrants who came to the United States after the enactment of the Immigration and Nationality Act of 1965. This legislation eliminated national-origins quotas and opened U.S. borders to persons from countries previously excluded.

Until 1965, most immigrants to the United States came from Europe. Today's immigrants, in contrast, come mainly from Mexico, Central America, China, India, and, secondarily, other Asian countries. Many of these immigrants work in distinctive labor market niches where they account for a high percentage of those employed. In some instances, they replaced earlier immigrants within the niche. Others carved out new niches of their own, often providing products and services not previously available.

Using American Community Survey (ACS) data from 2014, the most recent year available at the time of writing, table 1 shows the thirty occupations in which today's immigrants account for the largest share of employment. For each occupation, column 2 shows the share of immigrants employed and column 3 the average weekly wages of workers.

Table 1.

Occupations with Highest Shares of Foreign-Born Workers and Weekly Wages, 2013

These thirty occupations are those in which niching by specific groups of immigrants is most prominent. Although the ACS covers more than 300 occupations, ensuring the most accurate picture of the U.S. labor force, its classifications can be too broad to capture some very specific niches. For instance, nail salon workers—a specific niche we discuss later—occupy only a subgroup of the ACS occupation category "hairdressers and cosmetologists." Still, the ACS data on occupations do show the range of occupations in which immigrants cluster. The variety and diversity of these occupations span the skills and earnings spectrums. At one extreme are a variety of manually intensive craft niches in agriculture (graders, farmworkers), construction (plasterers, dry-wall installers, roofers, painters, carpenters, masons, tilers), and personal services (house-keepers, dressmakers, laundry workers, gardeners, hairdressers). These jobs tend to require physical skills that low-educated workers may have acquired already in their homeland and that are easily transferable to the U.S. labor market, such as construction skills and skills in personal services. Their pay scales vary considerably, from a low average in 2014 of $408 per week for housekeepers to $745 per week for carpenters. Sometimes immigrants take low-skilled jobs that build on work they did in their homeland without remuneration, such as when immigrant women work in the United States as nannies and housecleaners. Other immigrants learn skills in the United States for the jobs they take—for example, Vietnamese who become manicurists. At the low-skilled end of the work spectrum, the lowest-paying jobs are in agriculture, housekeeping, and hotel and personal services (housekeepers, laundry workers, shoe repairers), with weekly salaries below $500 per week in 2014. Moreover, there is often a wage gap in these jobs of around 20 to 30 percent between immigrants and natives.

At the other extreme are high-skilled science- and technology-intensive occupations for which demand has grown in recent decades, such as medical scientists, physical scientists, and computer software developers. Typically requiring college and postgraduate education, this work pays well. Computer programmers, the best paid among the occupations listed in table 1, earned on average $1,888 per week in 2014. Moreover, the table shows that in science, technology, engineering, and math jobs, such as physical scientists and computer software developers (as shown in Hanson and Slaughter 2016), immigrants earn the same as comparable natives, and sometimes even more. The knowledge of specific skills and the high quality of their academic education may be the reasons for such a reverse gap.

Table 2 shows that immigrants in the states where they make up large shares of the population dominate manually intensive niches, particularly in construction. For instance, in California, Nevada, New Jersey, New York, Maryland, Arizona, and Massachusetts in 2014, more than 61 percent of housekeepers and maids were foreign-born, while in California and Texas more than 65 percent of workers in construction occupations (roofers, painters, drywall installers) were foreign-born. And in all states with an important agricultural sector—California, Florida, Washington, and Oregon—more than 60 percent of farmworkers were immigrants. At the same time, 63 percent and 65 percent of medical scientists in Maryland and Massachusetts, respectively, were foreign-born. These two states have high-quality research and medical institutions.

Table 3 focuses on the numerically largest immigrant groups: Mexicans, Chinese, Indians, and the combined small Central American countries. For each of these immigrant groups, we show the five occupations that employ the largest share of the group. The niches identified in this table display an especially high degree of overrepresentation of these immigrant groups in the five occupations relative to native workers. We see in the table that Indian immigrants have the greatest occupational concentration, with 15 percent working as computer software developers and another 8 percent as computer analysts. These occupations offer high earnings and good career opportunities. The characteristics and evolution of the information technology sector, and Indians' role in it, are detailed later in this essay.

Like Indians, Chinese immigrants are heavily involved in computer-related and other high-skilled occupations, with 6 percent working as computer developers and 5 percent as managers and college instructors. In these jobs, both high-skilled Chinese and Indians build not only on schooling acquired before migration but also on the graduate education they obtain in this country, made possible by the accessible U.S. study visa program.

Unlike Indian immigrants, however, there are many Chinese in less-skilled and lower-paying jobs, such as cooks. Liang and Zhou (this issue) describe the expansion of different types and varieties of Chinese restaurants that cater not merely to Chinese but also to the broader U.S. population and that employ less-educated

Table 2.

Top Thirty-Five State-Occupation Groups with the Highest Shares of Foreign-Born Workers, 2013

Source: Authors' calculations from ACS 2014 data.

Note: The sample and variables are defined as in table 1.

Table 3.

Top Five Occupations for the Four Largest Immigrant Groups, 2013

Source: Authors' calculations from ACS 2014 data.

Note: The sample and variables are defined as in table 1.

Chinese workers. Chinese immigrants have creatively diversified this niche to include labor recruiters in specific regions of China and a domestic transport system to bring workers to restaurants across the United States.

Chinese immigrant involvement in low-skilled work dates back to the nineteenth century, when Chinese laborers were hired to construct the American railroad system; they also worked in service industries, such as laundries, that catered to coethnics in the urban neighborhoods where they settled (which came to be known as Chinatowns) as well as to other city-dwellers. Following enactment of the Chinese Exclusion Act in 1882, immigration to the United States from China was prohibited. The act was the first U.S. legislation to prevent a specific national group from immigrating; it would be followed by legislation in the 1920s that restricted immigration from other countries, especially countries other than those in northern Europe. When the Chinese Exclusion Act was repealed in 1943 and immigration resumed, Chinese gravitated anew to low-skilled jobs as cooks and launderers. However, after the Chinese government in the post-Mao period began aggressively promoting high-skilled economic development and lifting Maoist-era restrictions on emigration, growing numbers of high-skilled Chinese took advantage of U.S. postgraduate training and U.S. labor market opportunities.

By contrast, Mexicans, the largest foreign-born group in the United States, have the lowest average education level of any immigrant group (see Peri 2015) and have clustered in low-skilled manual occupations in construction (laborers), agriculture (farmworkers), and personal and food services (cooks, janitors). These occupations pay poorly, offer very limited opportunities for upward mobility, and subject workers to the risk of living below the poverty level. In several industries, Mexican immigrants and second-generation Mexicans occupy the least-skilled and lowest-paying jobs. Eli R. Wilson's essay (this issue) describes the work that Mexicans do in the restaurant industry in the "back of the house," mainly cleaning, restocking supplies, and preparing food; these jobs offer little if any opportunity for advancement. Contrasting their work with that of the better-paid, English-speaking "front of the house" customer service employees, Wilson notes that some second-generation Hispanics, being proficient in English as well as Spanish, have acquired language skills that enable them to attain jobs that bridge these two distinctive restaurant labor markets. In connecting the "low-skill" niche with the more dynamic, skilled customer service–oriented niche, these new immigrants, with their combination of manual and language skills, exemplify an important complementarity that opens up this industry not only to provide services, both new and old, in new ways but to expand employment opportunities as well.

Central Americans have a specialization pattern similar to that of Mexicans. Besides working as janitors and cooks, many of them—especially women—work as housekeepers and health aides. Those engaged in health care may improve their earnings opportunities over time. The expansion of the health care sector, particularly government-funded health care, combined with the aging of the U.S. population, has contributed to specific labor shortages, such as of licensed nurses. Such market forces may exert an upward pressure on the earnings possibilities for immigrant workers in this field, especially those who upgrade their skill sets and learn English. Like bilingual restaurant workers in "bridge" jobs, bilingual health care workers are especially well positioned to take jobs that provide a bridge between U.S.-born doctors and the fast-growing group of Spanish-speaking patients. (Hispanics now constitute the largest immigrant group in the United States.) Ming-Cheng M. Lo and Emerald T. Nguyen (this issue) describe the experiences of bilingual Hispanic health care workers, including the dilemmas they face in attempting to conform with professional standards while addressing cultural practices of Hispanic patients that are premised on different norms. They emphasize that more support and institutional change are needed to allow for effective cross-cultural bridging between doctors and patients.

Immigrants from other countries also play a central role in specific occupations or segments of occupations. For example, Vietnamese immigrants, who account for less than 1 percent of the U.S. population, are heavily involved in the nail care sector—the least-skilled and poorest-paying sector of the beauty industry—across America (see Eckstein and Nguyen 2011). Vietnamese have transformed the nail care industry and in so doing created demand for their work. They established "McNails," walk-in shops offering manicures and pedicures at a fraction of the price of beauty salons. Vietnamese immigrants have been easily able to do this work, which requires minimal English fluency. Before Vietnamese created Mc-Nails, only the well-to-do could afford nail care in the high-end hair salons that offered expensive manicures and pedicures as a secondary service for their clientele. The new model of nail care provided by Vietnamese has expanded demand for their services by lowering their cost, so that nail care is now within reach for people who previously could not afford it.⁵ Standards for nail beauty in due course have risen, further expanding demand for manicurists and pedicurists.

The creation of this new service and market has benefited Vietnamese women, both as shop owners and as employees. However, conditions in nail care salons are far from ideal. Earnings, being contingent on the number of customers a salon attracts—which varies seasonally—are low and variable, and workers are exposed to toxic supplies. In addition, opportunities for advancement are minimal, typically only to those who open their own salon; the most ambitious open multiple salons in different locations.

Many female immigrants from the Philippines—another of the top ten sending countries today—secure mid-skill jobs in nursing, a niche created by the U.S. and Philippine governments. U.S. immigration authorities extended special work visas to Philippine-trained nurses to meet the rising demand for nurse care in the United States that arose from both the aging of the American population and cost-cutting on the part of hospitals and other medical institutions. Nurses cost less than doctors to employ, and Filipina nurses cost less than American nurses. The Philippine government promoted the labor export strategy on the presumption that nurses who go overseas send remittances to the families they leave behind, providing a valuable source of income not only for the recipients but also for the government, which needs hard currency to finance imports and foreign debt payments. Meanwhile, private schools in the Philippines took advantage of the demand for nurse training for the U.S. labor market—to the point that they trained an oversupply of nurses relative to the number of nurses the United States would admit from the Philippines. While the schools profited, students bore the costs of training for U.S. jobs they could not attain. Yasmin Y. Ortiga (this issue) describes the unfortunate and unintended consequences of the outsourcing of U.S. health care training.

Other immigrant groups are associated with local labor market niches in the cities where they mainly live. For example, many Ethiopian and Eritrean immigrants in Washington, D.C., work as taxi drivers, an occupational specialization they acquired in the United States in response to local demand. Their involvement in this niche is city-specific: most immigrants from these countries live in the U.S. capital.

Black immigrants from Africa and the Caribbean are also associated with occupational niches. Hamilton, Easley, and Dixon (this issue) document that while foreign-born blacks, especially those from the Dominican Republic, Ghana, Nigeria, and Ethiopia, are likely to be employed in niche occupations (70 percent), U.S.-born blacks are the least-niched black group. U.S.-born blacks earn less than the other black groups they studied, but immigrant niching does not seem to explain this earnings differential.

Another new immigrant niche that mainly involves immigrants from Central America, the Caribbean, and the Philippines has arisen in response to demand for housekeeping and child care among the U.S. middle class. In providing affordably priced care, these immigrants have also generated demand for their services (see Brown 2011; Kasinitz and Vickerman 2001), such that middle-class women continue to work after they have children, with positive effects on their long-term earnings and their careers (see Cortés and Tessada 2011).

Xiaochu Hu (this issue) shows that highly educated immigrant groups also benefit from female niche work, including unpaid niche work. She analyzes how highly educated Chinese women benefit from the unpaid, family-based child care provided by their China-based parents, mainly their mothers. Taking advantage of the high priority given to family members in the current U.S. immigration preference system, Chinese grandparents come to the United States on special short-term visas. Hu shows that the unpaid child care provided by temporary immigrant grandparents increases the probability that their immigrant daughters with children will work for pay. Other immigrant groups also turn to immigrant grandparents for unpaid child care.

THE FACTORS ACCOUNTING FOR IMMIGRATION NICHE SPECIALIZATION

To organize our thinking about immigrants in labor market niches, we focus on four sets of factors that contribute to the new immigrant labor market niching: the skills that immigrant groups have to offer; their ability to address existing demand or create demand for new and expanded goods and services; the institutional practices and regulations of occupations; and the nature and strength of immigrant group ties that are useful in the world of work. These factors together create, sustain, and, under certain conditions, transform immigrant niche specialization, with other factors also playing a role at times.

Immigrant Skill Sets and Demand for Labor

The work done by immigrants hinges on demand for their skill sets. Many immigrants offer abilities and skills that differ from those of the native-born. These skills may include not just craftsmanship and specific competencies but also broader attributes such as a willingness to work, ability to endure outdoor conditions, punctuality, work ethic, and stamina.

The so-called new immigrants arrived in the United States as the economy shifted from being predominantly manufacturing-based to predominantly service-based, and they contributed to making this transformation possible. The shift foreclosed certain labor market options, while opening others. The industrial jobs that had employed Southern and Eastern European immigrants from the early to the mid-twentieth century declined as businesses moved their production offshore to countries where labor was cheaper and technological changes and mechanization reduced overall demand for manual labor in manufacturing. The manufacturing jobs that remain in the United States and employ the new immigrants are low-skilled jobs in the food-processing and meatpacking industries.

Interestingly, immigrants have displayed a high degree of versatility, filling niches in the service sector that require face-to-face interactions and cultural sensitivity; some observers in the 1980s thought that these requirements were not conducive to immigrant labor market incorporation. The ability of immigrants to introduce new services—for instance, in the food and restaurant sector (think of the current ethnic variety and new fusion varieties of restaurants in many cities)—have increased differentiation, adding consumption options for natives and improving their own economic welfare. This is documented for the restaurant sector by Francesca Mazzolari and David Newmark (2012), who show that the presence of immigrants widely increases the supply of restaurant varieties.

In other sectors, immigrants may displace native-born workers when employers prefer to hire the foreign-born if they perceive them to be more skilled, more disciplined, or willing to work for longer, less convenient hours or at lower pay. Immigrant contributions strengthen the economy and benefit consumers when lower costs reduce prices for the goods produced or the services offered. (Such an effect on local service prices is shown in Cortés 2008.) However, the natives or previous immigrants competing with new immigrants for jobs can experience reduced opportunities and downward pressure on their wages.

For several cognitive- and analytical-intensive occupations, new immigrants sometimes offer skills that U.S. companies strongly demand and that U.S.-born workers do not adequately provide because of the fast-growing demand. In particular, foreigners have contributed to innovation and productivity growth in the science and technology sector (see Peri, Shih, and Sparber 2015; Kerr and Lincoln 2010). Highly skilled immigrants have been crucial to the growth during the last thirty years of the information technology (IT) sector—which has revolutionized production in many industries—by bringing their skills and abilities to IT-intensive jobs and science, technology, engineering, and mathematics (STEM) jobs (see, for instance, Hanson and Slaughter 2016).

Although, as previously noted, Indians have played an especially important role as workers, entrepreneurs, and professionals in the IT and computer sector, they are not the only immigrant group to contribute to the development, transformation, and transnationalization of this sector. So too have Chinese and Taiwanese (see, for example, Yu-Ling Luo and Wei-Jen Wang 2002) and Israelis, as analyzed by Steven J. Gold (this issue).

Foreign-born workers are attracted to U.S. high-tech companies at the cutting edge of the industry worldwide because they pay well by international standards, and also because demand for electrical engineers, computer programmers, and software developers has soared since 1980. Many of the immigrants hired for these jobs are well trained abroad—for example, at India's famous Indian Institutes of Technology or in China's top universities. They obtain these coveted jobs because, on the one hand, they are highly skilled, and on the other, because U.S. immigration policy makes their employment possible. The United States prioritizes their admission by allowing U.S. employers to hire skilled foreign labor on special H-1B visas, for a maximum of six years. Since the turn of this century, over 80 percent of H-1B visas have gone to highly educated foreign professionals in computer-related occupations, and most of those have gone to Indians. These workers have been fundamental to Silicon Valley's ability to establish and maintain a global competitive edge in information technology.

Building on U.S.-acquired skills, capital, and networks, Indian immigrants have also formed their own start-up companies, in India as well as in the United States. In India, they have developed businesses that complement the work of U.S. firms. U.S. multinational companies in the high-tech sector have also turned to high-skilled, well-trained Indian immigrants to manage the subsidiaries they have established in India to capitalize on the talent and lower wages in the Indian market. In so doing, Indian immigrants have transnationalized, as well as transformed, this initially exclusively U.S.-based niche.

New immigrants also meet the demand for labor that native-born workers shun. Immigrants, for example, increasingly dominate hard, physically demanding, outdoor jobs in the agriculture and construction sectors. Even in skilled sectors of the labor market, immigrants fill many of the jobs that native-born workers find unattractive because of where they are located or the conditions of work. For example, many doctors from India work in the inner cities, where their U.S.-born counterparts resist working. Their willingness to take these positions is good for minority and poor patients in the inner cities, the economy, and the health of Americans.

In the last half-century, the entry of large numbers of native-born women into the labor force has in turn increased demand for low-paid, low-skilled labor to do the housekeeping and child care work that women used to provide, unpaid, within the household. Central American and Mexican immigrant women are employed for much of this paid labor.

Overall, new immigrant niches have evolved mainly in response to the growth and differentiation of the service sector—from manual and personal services for which there still is high demand (housekeeping, food preparation, child care, personal assistance) to knowledge-intensive and cognitive services at the other extreme (high-tech, human resources, research). New technology, new tastes, and new demand have interacted with the variety of skills, abilities, and attitudes of immigrants to create new niches and expand existing ones.

Institutional Regulations and Practices

In general, the federal government sets immigration policies that determine which foreigners, with which skill sets, may immigrate with work rights, and government policies dictate work conditions and requirements at both the local and national levels. The federal government also prioritizes the admission of foreigners with certain skills, as discussed earlier in the case of Indian IT workers and Filipina nurses. In addition, businesses, business groups, and other nongovernmental groups establish practices that affect immigrant work experiences.

Labor regulations also affect the work that immigrants do legally and, by default, illegally. Some immigrant groups can establish a footing in regulated work, while others face barriers. Many states limit jobs that require licenses to U.S. citizens and legal permanent residents and offer qualifying tests only in English or selective foreign languages, such as Spanish. Non-English speakers can qualify for licensed jobs only when the exams are offered in languages they know. For example, many Cuban doctors who immigrated with little proficiency in English and with training that did not meet U.S. standards failed tests to qualify for practicing medicine in the United States (Eckstein 2009, 99). Cuban American state legislators in Florida, where most Cuban immigrants settled, tried to get the state to bend regulations for Cuba-trained doctors. Otherwise, the Cuba-trained doctors who failed the Florida qualifying tests needed to find other lines of work.

Even low-skilled manicure work requires licensing, although the requirements are not as stringent as for doctors. Vietnamese have accessed nail care jobs, not merely because they attained the requisite skills, but because many states where they have settled offer the licensing exams in Vietnamese. Initially accessing the jobs informally, Vietnamese established themselves in the sector and then successfully pressed for the licensing exams to be offered in their native language. Thus, Vietnamese salon owners have been able to recruit low-wage workers from their homeland who easily meet licensing requirements.

Liang and Zhou (this issue) highlight the dependence of immigrant labor market niche involvement on immigrant employment agencies. With Chinese employment agencies channeling immigrants from certain regions of China to jobs across America—for example, in the restaurant sector—Chinese immigrants have become less dependent on the local labor market where they initially settled for work and Chinese businesses have become less dependent on local labor markets for workers. Supply and demand for certain types of labor have therefore become less geographically constricted, allowing for greater efficiency in matching workers' wants to employers' needs. These immigrant employment agencies, in turn, contribute to a professionalization and formalization of immigrant job recruitment.

Other, less formalized, non-state-based institutional practices also influence immigrant labor market involvement. Banks, for instance, may discriminate against immigrants on the presumption that, with their limited credit history, if any, they are high-risk borrowers. In the absence of access to bank capital, entrepreneurial immigrants have gravitated to activities that do not require a large initial investment, such as small food and concession stands. Other immigrants have established their own banks to fill the lending gap. For example, wealthy Cubans who fled their homeland after Castro came to power mainly settled in Miami, where some of them established banks that lent to fellow Cuban immigrants on the basis of trust, including trust established in Cuba before moving to America (Portes and Stepick 1993). The Small Business Administration (SBA) also favored Cuban immigrants over others in Miami. Thus, an exceptionally large number of Cubans opened small businesses in the city. Although they initially catered to persons from their shared homeland, over the years the more entrepreneurial businesses have reached out to others in the city, especially to the other Spanish-speaking Latin Americans who have also settled in Miami in recent decades. Cuban entrepreneurs have benefited from their command of Spanish and their cultural capital in the "new Miami," which has been dubbed the "northernmost Latin American city."

Vietnamese manicurists exemplify yet another source of investment capital to which immigrants have turned in the absence of access to bank capital: pooled family funds. Business opportunities in nail care are limited, but with pooled funds, Vietnamese have been able to enjoy the economic mobility associated with transitioning from being a worker to owning and managing a business (Eckstein and Nguyen 2011).

The least-skilled immigrants and those who came to the United States undocumented are mostly confined to the occupations that workers with better options leave unfilled, mainly in the agricultural and construction sectors. These jobs have the lowest entry barriers and are minimally protected by labor regulations. The work is low-paid and seasonal, with very high turnover, and it subjects workers to harsh working conditions; workers in agriculture, for instance, are exposed to toxic herbicides and pesticides, as well as to extreme heat or cold. Although many of the foreign-born in these jobs are responding to a demand for their labor, they often have been unable to attain immigration visas and the legal protections provided by legal entry. As such, they are particularly vulnerable to employer abuse and fear of deportation. Table 2 shows that the vast majority of farmworkers in California, Florida, and Washington—states with large agricultural sectors—are from Mexico. The jobs usually pay minimum wage, at best, and offer workers little legal protection. Undocumented immigrants represent a large share of those workers.

Regulations have combined with practices and traditions to attract specific immigrant groups not only to private-sector niches but also to some public-sector niches. The Irish, for instance, have a long tradition of working as police officers and firefighters in the cities where they mainly live (notably New York and Boston). In general, however, citizenship requirements result in public-sector niches being occupied by more second-generation immigrants than first-generation immigrants.

Among return immigrants, a reverse type of niching may even take hold. Michaël Da Cruz (this issue) details the establishment by U.S. companies of call centers in Mexico to take advantage of much cheaper labor costs than in the United States. They rely on Mexicans who grew up in the United States and thus are proficient in American-style English; many of these returnees were deported because they were not authorized immigrants with rights to work in the United States. Bilingual expertise is a form of cultural capital, in this case in Mexico, for persons without formal credentials for more-skilled jobs. U.S. companies have set up similar call centers in Central American countries that also draw on U.S.-attained immigrant cultural capital.

Immigrant Network Niche Formation, Maintenance, and Transnationalization

People rely on social contacts to attain jobs, and immigrants are no exception, even when they turn to immigrant employment agencies. Immigrant groups become entrenched in distinctive lines of work through informal ties among "their own." Historically, friends and family have told immigrants about job opportunities where they work or in the same line of work and provided them with job contacts (La-fortune and Tessada 2012), and that remains true today. The tendency of new immigrants to attain work in "immigrant enclaves" has been analyzed at length by sociologists and economists (see, for example, Altonji and Card 1991; Card and DiNardo 2000; Gold 2000; Waldinger 2001; Wilson and Portes 1980).

Immigrant women are known to rely especially heavily on personal ties for securing work. Their networks channel them into work with clusters of other women from their country of origin (see Sassen 1995). Some occupations in the service sector, such as housekeepers and maids, are dominated by immigrant women from Mexico and Central America, who often learn of and secure jobs through people they know not only in the United States but also from their communities of origin in their homeland. Immigrant groups—Brazilians in particular—are known to informally sell rights to cleaning jobs as they leave them, either to take other jobs or to return to Brazil (Braga Martes 2011). Once some members of an immigrant group establish a beachhead in a certain line of work, other group members, including new arrivals, gravitate to the same work. Immigrants like to work where they know others.

Informal social networks thereby serve as fundamental building blocks for (often gender-specific) immigrant group labor market niching. The inclusionary dynamic within immigrant groups excludes immigrants from other countries, as well as the native-born, from attaining job information and job contacts. Such exclusion is not by design, but rather an unintended consequence of in-group relations. Inclusionary-exclusionary practices transpire across the labor market in work commanding different levels and types of skills.

The network dynamics that result in distinctive immigrant group concentration in specific niches extends to the small business sector, even to self-employment. The same networks that allow workers to find jobs among their coethnics encourage investments and firm ownership by immigrants in those niches. William Kerr and Martin Mandorff (2015) discuss Koreans coming to own most of the dry-cleaning shops where they previously worked, and Eritreans and Ethiopians owning and operating the taxi companies that first employed them. Meanwhile, Chinese own not only restaurants but, in recent years, the bus companies that transport Chinese to work in restaurants across the United States. Thus do immigrant networks contribute to business clustering. Small business ownership often builds on the ties as well as the expertise that immigrants from specific countries first acquired as workers in particular lines of work. Alternatively, newly arrived entrepreneurs and investors may focus on a sector where they already have ties with coethnics. Thus, both entrepreneurial and labor-driven immigrant networks contribute to the concentration of specific immigrant groups in specific economic niches.

The in-group ties that contribute to labor market niching may even extend beyond U.S. borders, and not only to immigrant homelands but also to other countries. The close ties that today's immigrants maintain with friends and family in their country of origin have contributed to the transnationalization of niche activity in a variety of ways. Immigrant groups may develop their niche "vertically" across borders by establishing supply chains that extend to their country of origin. Because owners of niche businesses may prefer to hire immigrants from their homeland when looking for new workers, the supply chains may center on labor recruitment. Their common language makes communication easy, and they also share feelings of trust and loyalty. Moreover, the new arrivals are likely to work for less pay than more-established immigrants and to tolerate less attractive work conditions. The very establishment of an immigrant group niche in the United States may, in turn, inspire people in the homeland to acquire the skills required to work in the niche, knowing that, upon immigrating, they are more likely to attain work easily on the basis of their transnational ties. For example, Vietnamese first became involved in the manicure business in the United States, but once they established the niche, others began to train for the work in Vietnam so that they could secure employment as manicurists upon their arrival in the United States.

The networks of immigrants consolidated within U.S. niches can also evolve into transnational connections. For example, some immigrant group restaurateurs draw on food supply chains in their homeland. Economists have measured for a long time the transnational impact of immigrant networks on business by showing that countries with larger communities of immigrants from a specific origin tend to trade more with that country and also invest more there (see Rauch and Trindade 2002). By representing a bridge between two cultures and countries, the network of migrants in a labor market niche produces economic ties with the country of origin, promoting foreign investment and business there.

Members of an immigrant group may also take their niche work to other countries, expanding the niche "horizontally." Vietnamese, for example, have established nail salons in Europe that build on the U.S. "McNails" model, inspired by the work of friends and family in the United States.

The experience of Indians who have drawn on the capital, expertise, and networks they developed in Silicon Valley to establish related businesses in India points to another form of niche transnationalization: in what has been dubbed "brain circulation" (Saxenian 1994), Indians transfer not only technology but their expertise to the country from which they originated. The success of Indians in this high-tech niche has come to be transnationally embedded through networks of immigrants, return immigrants, and immigrants with economic interests spanning the United States and India. Their high-tech activity is no longer based in the American labor market (see Commander et al. 2008).

The top research universities have also come to be dominated increasingly by scholars immigrating from select countries. As universities have globalized the pool from which they recruit their "best and brightest," competition has become steeper for the U.S.-born. More competition allows for higher-quality scholars in universities, although it concomitantly crowds out opportunities for native-born researchers.

Foreign-born professors in U.S. universities, in turn, recruit graduate students from top schools in Europe, Asia, Latin America, and Israel through their connections with and knowledge of the schools these students attended abroad. Recruiting foreign graduate students creates networking channels for research projects, coauthorships, and technological transfer between U.S. and foreign universities. Moreover, immigrant groups, sometimes from particular foreign universities, dominate niches in U.S. university departments—for example, Russians in mathematics, Israelis in engineering, and Indians in computer science.

NICHE SPECIALIZATION AND ECONOMIC OPPORTUNITIES

The niches in which immigrant groups get involved often affect their long-term economic prospects. Niches differ substantially in the opportunities they afford. Some are relatively "flat," offering very limited opportunities for vertical career improvement. Other more complex and differentiated niches provide opportunities for immigrant job advancement and earnings improvements and contribute more to the economy at large.

Immigrant groups that get involved in low-wage, low-skilled niches experience few opportunities for economic advancement or career advancement. Most Mexicans and Central Americans have been stuck in low-paying niches in agriculture and construction, where their career opportunities are limited. This is a consequence of both their lower levels of schooling and the location of these jobs, which are primarily found in rural and economically stagnant communities. Thus, the economic possibilities for these immigrants are limited, both within and outside these niches.

In contrast, immigrant groups involved in more-skilled niches that offer within-niche economic opportunities are well positioned to build on their human and social capital. They may not only respond to but also create opportunities for themselves, including through niche transnationalization. Typically, niches in the information technology, medical science and research, and applied life science sectors offer such opportunities. Indians, highly educated Chinese, Israelis, and other Asian groups have been major beneficiaries of such expansive niche-based opportunities.

A related and interesting issue we know little about concerns the intergenerational transformation and evolution of niches. Does the second generation of immigrants find success within a niche, possibly occupying its higher ranks (that is, moving from workers to employers and managers)? Or do they find success after leaving the niche? Roger Waldinger's (1999) descriptions of some niches typical in New York (for example, in the garment and fashion industry) imply that second-generation immigrants (such as Italians and Israelis) have succeeded by climbing the job ladder to become designers and traders within that niche. Other researchers emphasize that the second generation tends to leave the parents' niche to achieve economic success. Second-generation Vietnamese, for example, rarely work as manicurists, because the work offers no stable income, exposes them to toxic chemicals, and pays poorly (Eckstein and Nguyen 2011). In this issue, Eli R. Wilson describes how a bilingual, U.S.-born second generation generates its own upward growth opportunities in the restaurant industry by advancing from the lower-ranked jobs typically filled by the first generation to the upper tiers.

CONCLUSION

Immigrant specialization in labor market niches that build on immigrant social networks and sometimes also on immigrant social institutions helps immigrants attain jobs upon their arrival in America. This specialization contributes to an efficient allocation of skills to jobs as immigrants with different human and social capital assets attain jobs that fill labor market needs and broaden demand for labor by creating new products and services. New immigrants respond to but also create markets for their labor, as sociological dynamics help us understand. The opportunities open to immigrants depend on the match between their assets and the robustness or flatness of the niches in which they become engaged.

Immigrants respond to conditions where they settle as best they can, not necessarily cognizant of the macroeconomic efficiency of their labor market involvements. Niching can be a valuable channel for immigrant labor market integration while simultaneously generating economic growth and efficient specialization, provided it does not introduce distortionary barriers and exclusion through niche-based immigrant institutions but keeps those niches open to the forces of competition. The high-skilled immigrant niches contribute the most to the economy, even if they leave some highly qualified U.S.-born workers on the sidelines.

This introduction has pointed to ways in which concepts and insights from sociology and economics can be combined to advance our understanding of the conditions that contribute to the formation of distinctive new immigrant niches and their unintended as well as intended consequences. The essays that follow examine in rich detail both general and specific immigrant labor market engagement from diverse disciplinary and methodological perspectives. Together, they deepen our understanding of how and why different immigrant groups have become associated with different lines of work across the skill spectrum, with different consequences for immigrants, for the native-born, for the country at large, and for immigrant countries of origin. We hope that these essays will inspire other studies that deepen our understanding of immigrant labor market experiences in the globalized economy in which we live.