Population Trends
The Fastest-Growing U.S. States: Population Change in the ACS5 Era
Census population estimates show a clear story: the South and Mountain West gained, the Midwest and Northeast stagnated. Here's the data, and why it matters.
By City Zip Compare Editorial · March 15, 2026 · 7 min read
Where Americans move shapes everything that follows: housing prices, school funding, congressional apportionment, even where major retailers open stores. The Census Bureau's annual population estimates and the ACS5 5-year averages tell a consistent story over the last decade — Americans have been moving south and west.
The five fastest-growing states
Across the most recent ACS5 release, the largest absolute gains have been concentrated in: Texas, Florida, North Carolina, Arizona, and South Carolina. As a share of starting population, Idaho, Utah, Montana, and Florida lead. Three forces drive this: lower cost of living, lower or no state income tax, and warm climates.
- Texas: largest absolute population gain
- Florida: high absolute and relative gain
- Idaho: highest percentage growth
- North Carolina: research-triangle and Charlotte metro pull
- Arizona: Phoenix and Tucson metros
Where population shrank
West Virginia, Mississippi, and Illinois have lost residents. Several Northeastern states (New York, Pennsylvania) are roughly flat in absolute terms but losing share. The drivers are aging populations, outmigration of young workers, and weak job growth in interior metros.
Why the trend matters beyond bragging rights
The 2030 Census will redraw the U.S. House. States that grow take seats from states that shrink. Internal migration is the single biggest driver of those shifts, and the ACS5 is the cleanest free dataset for tracking it at the state, metro, and county level.
Frequently asked
›Why does City Zip Compare use ACS5 instead of the decennial census?
ACS5 is updated every year and reaches down to the ZIP-code level. The decennial census is more precise but only published once every ten years and only at coarse geographies for most variables.
›Does ACS5 count immigrants?
Yes. The ACS asks every U.S. resident regardless of citizenship status; foreign-born residents are included in population counts.
More in Population Trends
Median Age by U.S. State: The Demographic Map of America
Maine and Florida are the oldest states. Utah is by far the youngest. Median age is one of the cleanest single signals of a state's demographic future.
The Fastest-Growing Cities in Texas (2026 Edition)
Texas added more residents than any other U.S. state in the most recent ACS5 vintage. Most of that growth is concentrated in a handful of metros — and within those metros, in a handful of suburbs. We map them.
The 25 Fastest-Growing ZIP Codes in the United States (2026)
Based on Census ACS5 population estimates, we identify the 25 fastest-growing ZIP codes in the country — and the structural drivers (jobs, housing supply, climate) behind each one.
Source: U.S. Census Bureau, American Community Survey 5-year estimates. Data: census.gov/programs-surveys/acs.