The Rise of Cohabitation in the United States: New Historical Estimates

Catherine A. Fitch, University of Minnesota
Ron Goeken, University of Minnesota
Steven Ruggles, University of Minnesota

This paper presents new census-based estimates of opposite sex unmarried partners in the United States for the period from 1950 to 2000, including numbers of cohabiting couples and descriptive characteristics of these cohabiters. The 1990 and 2000 censuses included specific responses for “unmarried partner” in the relationship question; previous censuses classified these individuals in the broader “partner/roommate” or “partner/friend” categories making them more difficult to identify. Using the Integrated Public Use Microdata Series (IPUMS), we provide estimates of cohabitation that improve on previous methods. Instead of devising a simple set of rules to distinguish cohabiters, we develop models based on the 1990 and 2000 censuses to identify the best predictors of cohabitation. These models are then applied to earlier census years to estimate predicted probabilities of cohabitation.