170 years of living arrangements in the United States

Over the past 170 years the United States (US) has undergone demographic, structural, and cultural changes that are reflected in–and a reflection of–changes in living arrangements. We provide the first account of life-years spent across different living arrangements for the entire US population between 1850–2021. We also describe changes across generations born in the 1860s, 1900s, and 1940s. We use harmonized census data from the Integrated Public Use Microdata Samples (IPUMS USA). We classify living arrangements broadly into living alone, only with primary kin (partners, parents, and children), and in extended households, and into more detailed sub-categories including, for example, single-parent primary-kin households and extended families. Our results reveal three distinct systems of living arrangements. A “large household” system prevails between 1850 and 1940, starting from similar shares of life years spent in extended and primary-kin households, with a steady growth of the latter in line with rising life expectancy. This is followed by an era of “primary kin household” dominance between 1940 and 1980, when gains in life years spent with primary kin outpace life expectancy increases, and living alone emerges. From 1980 onwards, a “diversified” system emerges, with declines in primary-kin households in favor of a more varied set of arrangements. Our results show how historical changes in population mortality and age structure combine with social change to affect household composition, and invite scholarship on families and households to consider the repercussions of social and demographic change for living arrangements across the population age distribution.