Ratio of housing units to single adults (25+) and coupled households

The declining ratio since 1980 means that more people are doubling and tripling up, and adult children are living with their parents longer, because a shortage of homes prevents them from forming new households.

ACS = American Community Survey 1-year samples; 2005 sample excluded because of changes to how the population in group quarters is counted between 2005 and 2006.
The ratio's numerator is the total number of housing units in the U.S., and the denominator is the total U.S. population age 25 or older minus the number of married and unmarried/cohabiting couple households. Subtracting coupled households eliminates double-counting housing demand for these households.
Note that the Decennial Census did not track unmarried couple households until 1960.
Chart: Shane PhillipsSource: U.S. Census Bureau, Decennial Census and American Community Survey 1-year samplesGet the data Download image