What Accounts for the Increase in the Number of Single Households?

Between the mid 1970's and the beginning of the 2000's the share of single females grew dramatically in the U.S. (from 21% to 32%). So did the share of single mothers (from 10% to 14%). At the same time relative wages within and between sexes underwent huge changes. In this paper we measure the contribution that changes in relative wages had in accounting for these and other demographic facts. We construct a model where agents differ in sex, take marital status and fertility decisions and invest in their children's human capital. Our findings show that changes in relative earnings potential account for: i) almost ninety percent of the observed change in the share of single women, and ii) all the observed change in the share of single mothers, with a sharper increase among poor women. This occurs mainly through a drop in the model economy marriage rate that mimics the pattern found in the data.