Where American households are biggest and smallest
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The average household in Imperial County, California holds 3.49 people. In St. Louis, it holds 1.92. That difference of more than one and a half people per home, is the difference between a place where families are and a place of where people live by themselves.
The national average is about 2.5 people per household and that average has been falling for a century.
Where households are biggest
| County | People per household |
|---|---|
| Imperial County, CA | 3.49 |
| Madera County, CA | 3.41 |
| Utah County, UT | 3.39 |
| Webb County, TX | 3.28 |
| Hidalgo County, TX | 3.27 |
Imperial, Madera, Webb, and Hidalgo are heavily Hispanic border and agricultural counties, where households more often include grandparents, adult children, and extended relatives all under one roof. That's partly culture and partly economics: pooling a household is how expensive housing gets affordable on farm and service wages.
Utah County is more about fertility. Provo and Orem sit in the most heavily Latter-day Saint county in the country, and Utah has the highest birth rate and the largest households of any state at 2.97 people. Big households there mean many children, not many generations.
Where they're the smallest
St. Louis has the smallest households of any county-level place over 100,000 residents, at 1.92.
Sumter County, Florida, which contains a retirement community, The Villages, averages 1.93 people per household, mostly retired couples and widowed residents living alone. The others are the dense professional cities: Manhattan at 2.00, Washington, D.C. at 1.99, Alexandria and Arlington in Virginia, and Denver. These are places full of young professionals living alone or with one roommate, in small, expensive units.
Meanwhile, St. Louis is a shrinking city with an aging population, high poverty, and lots of housing built for families that now holds one or two people. That's what long-term population loss looks like at the household level, a story we traced in how Detroit lost half its population.
The long decline
In 1940 the average American household held about 3.7 people. Today it's around 2.5. Families got smaller, people started living alone in far greater numbers, and Americans got wealthy enough to afford their own place, which most people choose when they can.
The consequences run through everything. Falling household size means the country needs more housing units even when the population is barely growing, because the same number of people now need more homes to live in. It's one of the quieter reasons housing demand keeps outrunning supply, and it's why places can add housing for years while still feeling short.
Household size also cuts against per-person income comparisons. A county where households are large will show a higher median household income than its actual standard of living implies, because more earners are pooled into a single household. It's worth remembering when reading our income by county rankings.
Sources
Average household size is from the U.S. Census Bureau American Community Survey 5-year estimates, table B25010, limited to county-level places with at least 100,000 residents. Household size counts people living in occupied housing units and excludes people in group quarters such as dorms, prisons, and nursing homes.
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Which US county has the largest households?
Imperial County, California has the largest average household size among counties over 100,000 people, at 3.49 people per household, followed by Madera County, California at 3.41 and Utah County, Utah at 3.39. Utah has the largest households of any state at 2.97 people.
Why are households larger in some counties?
Two different patterns produce large households. In heavily Hispanic border and agricultural counties like Imperial, Webb, and Hidalgo, households more often include grandparents, adult children, and extended relatives, which reflects both family structure and the economics of expensive housing on low wages. In Utah County, large households come mainly from high birth rates and more children per family.
Why has American household size been shrinking?
The average fell from about 3.7 people in 1940 to roughly 2.5 today because families have fewer children, far more people live alone, and rising incomes let people afford their own space. One consequence is that the country needs more housing units even when population growth is slow, since the same number of people now require more homes.
