Between 1880 and 2000, the percentage of married men 60 and older living only with their wives in empty nest households rose from 19 percent to 78 percent. Data drawn from the US census show that more than half of this transformation occurred in the 30-year period from 1940 to 1970, bookended by moderate increases between 1880 and 1940 and very modest increases after 1970. Two literatures have presented demographic, cultural, and economic explanations for the decline in elderly co-residence with their children, but none adequately accounts for a sharp change in the mid-twentieth century. Both aggregate comparisons and multivariate analysis of factors influencing the living arrangements of elderly men suggest that economic advances for all age groups in the critical 30-year period, along with trends in fertility and immigration, best explain the three-stage shift that made the empty nest the dominant household form for older men by the beginning of the twenty-first century.