Dramatic fertility swings over the last 100 years have been the subject of large literatures in demography and economics. Recent research has claimed that the post-1960 fertility decline is exceptional enough to constitute a “Second Demographic Transition.” The empirical case for a Second Demographic Transition, however, rests largely on comparisons of the post-1960 period with the baby boom era, which was itself exceptional in many ways. Our analysis of the US instead compares the fertility decline in the 1960s and 1970s to the earlier 20th century fertility decline, especially the 1920s and 1930s.

Our findings affirm that both periods experienced similar declines in fertility rates and that the affected cohorts averaged the same number of children born over their lifetimes. In contrast to conventional wisdom, the mean age of household formation (by marriage or non-marital cohabitation) and first birth are almost identical for women reaching childbearing age in the 1920s and 1930s and today.