Change is the only constant: living arrangements in the United States, 1850–2021
Living arrangements are the reflection of demographic and social change. Using historical census data from the United States, Ginevra Floridi and Albert Esteve summarise 170 years of change in household structures. They identify three historical ages of living arrangements, and question assumptions about the traditionality of so-called “nuclear” households.
Living arrangements can reveal much about a society, as they both reflect and determine wider societal trends. Throughout modern history, two broad forces have restructured the population composition of living arrangements: demographic change, which determines who is alive at the same time to potentially live with; and social change, which encompasses cultural, political and macroeconomic forces that shape preferences and needs for living apart or together.
Expected years of life by living arrangements is a useful measure for summarising historical change. Based on life expectancy at birth, it indicates the number of years a fictitious cohort would live if they experienced the same mortality and the same living arrangement profiles as those prevalent in the population in a given year. It provides a means to capture change over time and break it down into the contribution of different age groups. In our recent study (Floridi & Esteve, 2026), we summarise life expectancy at birth by living arrangement over 170 years with available census and register data (1850–2021) and complement this by looking at changes across cohorts of people born in the same decade. We focus on the United States, a country that has seen a doubling of life expectancy at birth since 1850 while undergoing radical economic, policy, and cultural shifts.
Three historical ages of living arrangements
Figure 1 shows life expectancy at birth for available census or population survey years between 1850 and 2021. Expected years of life are distributed across three broad categories and seven sub-categories: living alone (alone); living with primary kin (couple only, two-parent, and single-parent households); and living in an extended household (kin only, mixed, or nonkin only).
Based on this cross-sectional look and complementary analyses, we identify three historical ages of living arrangements in the United States.
The first is a large household system (1850–1940). During this phase, years spent living alone represent a negligible share of population life years, which are evenly split between primary kin and extended households. Primary kin living absorbs most of the increases in life expectancy over the period, which are largely attributable to improved infant survival. Years spent in extended households look stable over the period, but this masks substantial heterogeneity: extended kin households continue to expand until 1940, while mixed households (kin and nonkin) fall as a result of the decline in live-in servitude and lodgers. During this phase, household types where children are born into primary kin and extended kin households grow in line with life expectancy, with mortality decline among infants and children being the main driver of changes in living arrangements.
A second age of primary kin dominance follows (1940–1980). Living alone rises quickly, especially among older females, which can be attributed to women’s survival after adult children’s exit from the household and the death of a male partner. Years spent with primary kin increase faster than life expectancy, and for all age groups. Meanwhile, extended kin-only households decline for the first time. This period is marked by rapid social change, as all age groups shift from extended to primary-kin (or solo-living) arrangements, with changes outpacing mortality decline. It is interesting to note that while this represents a brief phase of rapid social change during the post-war period, it has led to so-called “nuclear” households being widely regarded as traditional and normative in the United States (Nicholson, 2016).
1980 ushers in a new ongoing phase of diversification. We observe increases in living alone among younger age groups and males, with a stabilisation (and slight decline) in living alone for older females. Within the primary kin category, two-parent households with children decline in prevalence, while the share of couples without children, and single-parent households increases. Living in extended families returns to 1940s levels, with the rise concentrated among children and young adults. This has been attributed to racial/ethnic diversification of the population (Pilkauskas et al., 2020) and to economic constraints on economic independence (Ruggles, 2007). Again, it is worth emphasising that extended family households are common throughout the observation period, except for the relatively brief era of primary kin dominance.
Change across cohorts and future prospects
To complement our cross-sectional analysis, we select cohorts born in 1860–69, 1900–09, and 1940–49, and plot their living arrangements by age in Figure 2.
The 1860s cohort is emblematic of the diversity in living arrangements that characterised the second part of the 19th century. In the later cohorts, we observe a sharp decline in extended households, through the near disappearance of mixed households and the decline in extended family arrangements that characterised the early and mid-20th century. The 1900s cohort (aged around 40 in 1940) displays the initial shift towards primary kin living, and a marked increase in living alone at older ages, especially among women, due to high male mortality in this cohort. The 1940s cohort reached age 20 during the “baby boom” of the 1960s. Life courses in this cohort are structured around primary kin living: most individuals go from living as a child with two parents (until age 20), to living as a parent with children (ages 20–45), followed by couple-only arrangements once children move out (45 onwards). Again, women are more likely to spend their older ages living alone than men, due to differential survival.
We cannot provide a picture for the birth cohorts who have not yet reached later life. However, our period analyses (Figure 1) suggest that things will look different for those born in the 1960s, 1980s, and beyond. As the United States enters a diversified era of living arrangements, successive cohorts will experience more years spent living alone and in extended arrangements, including with nonkin. Within primary kin households, couples without children will rise in prevalence and may become the dominant category, while single parenthood rates will also increase. More recent birth cohorts are thus likely to experience the decline in two-parent households that have misguidedly been represented as the historical norm in the United States.
References
Floridi, G., & Esteve, A. (2026). 170 years of change in living arrangements in the United States using expected years of life: A research note. Demography. https://doi.org/10.1215/00703370-12546633
Nicholson, L. (1997). The myth of the traditional family. In Lindemann, H. Feminism and families (pp. 27-41). Routledge. https://doi.org/10.4324/9780203760413
Pilkauskas, N. V., Amorim, M., & Dunifon, R. E. (2020). Historical trends in children living in multigenerational households in the United States: 1870–2018. Demography, 57, 2269–2296. https://doi.org/10.1007/s13524-020-00920-5
Ruggles, S. (2007). The decline of intergenerational coresidence in the United States, 1850 to 2000. American Sociological Review, 72, 964–989. https://doi.org/10.1177/000312240707200606