#2005-03: The Rise of Cohabitation in the United States: New Historical Estimates.

ABSTRACT: The rise of cohabitation in the United States in the late twentieth century is an important component of the dramatic changes in marriage, family formation and childbearing (e.g., Bumpass, Sweet and Cherlin 1991; Bumpass and Lu 2000; Casper and Bianchi 2002; Manning 1995). This increase, first noted in the 1970s, was initially inferred from  household composition because few data sources collected direct information on couples “living together” (Glick and Norton 1977, Glick and Spanier 1980).

Research on cohabitation exploded in the 1980s as the trend accelerated and when longitudinal data sources, such as the National Survey of Families and Households, provided nationally representative datasets designed for studying cohabitation. Despite a wealth of new information on cohabitating couples—including the implications of cohabitation on family formation, relationship stability, childbearing and  child well-being—there are few estimates of cohabitation that assess the dramatic change over time (e.g., Bumpass and Sweet 1989, Bumpass and Lu 2000). Studies that examine cross-sectional differentials, such as race, educational attainment and place of residence, are even rarer.

This paper improves on previous attempts to infer cohabitation from the decennial census. The 1990 and 2000 censuses included specific responses for “unmarried partner” in the relationship question; previous censuses classified these individuals in broader “partner/roommate” or “partner/friend” categories. Our goal is to infer as best we can which individuals in the censuses of 1960 though 1980 would have described themselves as oppositesex unmarried partners if that option had been available on the census. We do this by first developing rules to identify households that are likely contain an unmarried partner, and then by applying a regression model to refine these measures.

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