Background: This study examines trends in affluence ‒ as indicated by high household income ‒ by household structure over the 1959 to 2017 period. I contrast the experiences of married-couple households, whose share of all households declined substantially over time, with those of single-parent households, cohabiting couples, individuals living alone, and people living with nonrelatives.

Methods: I use data from multiple censuses and the American Community Survey and logistic regression.

Results: Levels of absolute affluence rose substantially for all household types, reflecting rising living standards. Married-couple households were the most likely to be affluent and single-parent households were the least. Moreover, the affluence gap between married-couple households and all others widened. Married couples fared better because they experienced larger increases in wages and other important sources of income, such as from investments and retirement.

Conclusions: The findings suggest that married-couple households benefit from a collective work strategy and economies of scale that increase their likelihood of affluence. Positive selectivity into marriage may also have increased over time.

Contribution: This study provides timely new information on changing gaps in affluence by household structure during a period of substantial change in household living arrangements and economic well-being.