L.A. Story: Immigrant Workers and the Future of the U.S. Labor Movement

Appendix B. Adjusting for Changes in the U.S. Decennial Census Industry and Occupation Classifications, 1970 to 2000

APPENDIX B ADJUSTING FOR CHANGES IN THE U.S. DECENNIAL CENSUS INDUSTRY AND OCCUPATION CLASSIFICATIONS, 1970 TO 2000 The U.S. Census Bureau’s industry and occupation classification scheme changed significantly between 1970 and 1980, and again between 1990 and 2000; minor changes were made between 1980 and 1990 as well. It is necessary to adjust for these changes to reliably track historical trends over this period (as represented in table 2.3 and figure 2.2). To do so, the U.S. Census Bureau’s industry and occupation crosswalks for 1970 to 1980, 1980 to 1990, and 1990 to 2000 (U.S. Census Bureau 1989, 1994, 2003) were used to adjust all estimates for the occupations and industries shown in table 2.3 (and in table B.1 for the United States as a whole) to be consistent with the 2000 census industry and occupation codes.1 A step-wise procedure was used to adjust the 1970 to 1990 industry and occupation data to their 2000 equivalents. Each step involved using one or more of the three crosswalks to translate between the industry and occupation categories of adjacent census years. For example, translating the 1990 estimates to reflect the census 2000 classification system requires only one step, using the 1990 to 2000 crosswalk. By contrast, translating the 1970 estimates requires three steps: (1) using the 1970 to 1980 crosswalk to translate the 1970 codes into the 1980 categories; (2) 198 using the 1980 to 1990 crosswalk to translate the 1980 codes into the 1990 categories; and (3) using the 1990 to 2000 crosswalk to translate the 1990 codes into the 2000 categories. Translating the 1980 estimates requires two steps, moving first from 1980 to 1990 and then from 1990 to 2000. Changes in the occupation and industry classification schemes can affect both the estimates for the numbers of workers in each occupational group (the “population estimates” shown in tables 2.3 and B.1) and the estimates for the demographic composition of each. To adjust for this, the tables present weighted averages of the descriptive statistics for each occupation , where the weights represent the contribution of occupations to their respective 2000 occupation/industry category. For example, five 1990 occupations would have been classified as truckers had the 2000 occupational classification system been used in 1990: (1) supervisors and proprietors, sales occupations; (2) sales representatives, mining, manufacturing , and wholesale; (3) news vendors; (4) truck drivers; and (5) driver-sales workers. Very small portions of all but category 4 would have been classified as “truckers” in the 2000 system. To estimate the demographic characteristics for truckers in 1990 under the 2000 classification system, we estimate a weighted average of the demographic characteristics for each of these five occupations, where the weights are the proportion of the total estimate contributed by the respective occupation. Some of the occupations shown are more affected by changes in the coding scheme than others. For drywallers, the occupational classification is largely consistent from 1970 to 2000; the codes from 1980 through 2000 are fully comparable (U.S. Census Bureau 1994, 2003), and the change in classification from 1970 to 1980 is small (U.S. Census Bureau 1989). For garment workers, the codes also have been relatively stable , with over 90 percent of garment workers classified within a single industry code since 1970. By contrast, janitors and truckers have been more drastically affected by changes in the occupational classification system over time. Despite this, our adjusted and “unadjusted” results (not shown here but available from the author on request) are very similar for all four occupations.2 Table B.1 summarizes the adjusted data for the United States, using the same procedures employed to construct table 2.3. These data are also the basis for the U.S. data shown in figure 2.2. Appendix B 199 TABLE B.1 Employment in Selected Occupations in the United States, by Race, Ethnicity, and Nativity, 1970 to 2000 Occupation 1970 1980 1990 2000 Drywallers Native-born white 85.4% 79.8% 71.2% 54.6% Foreign-born white 4.2 3.4 2.3 1.6 Native-born black 4.1 4.2 4.7 4.1 Native-born Hispanic 3.6 5.8 5.5 5.9 Foreign-born Hispanic 1.6 4.7 13.2 29.6 Other 1.0 2.3...