The South was the only U.S. region whose population grew in every broad age group from April 2020 to July 2025, according to new Census Bureau estimates.
The region added about 7.6 million people, a 6.0% increase that was nearly twice the nation's 3.1% growth. The South reached an estimated 133.8 million residents in July 2025.
Its under-18 population grew 1.1%, while the same age group declined 4.1% in the Northeast, 3.9% in the Midwest and 5.7% in the West.
The South also was the only region with growth among people ages 45 to 64, though the increase was just 0.1%, or about 19,000 people. The region's population age 65 and older grew 17.5%.
Adults ages 25 to 44 posted the South's fastest non-retirement-age growth, rising 9.0%, or about 2.9 million. The 18-to-24 population increased 5.0%.
Metro counties drove much of the change. Southern metro counties grew 6.7%, and the Census Bureau said outlying counties on metro edges grew fastest across all age groups.
The agency attributes regional patterns to the aging of baby boomers, migration and fertility. Its estimates describe net population change and do not assign one cause to every county or household move.
Vintage 2025 incorporates detailed results from the 2020 Census into the estimates base for the first time. Census advises comparing years within the same vintage because each annual release revises the entire post-2020 series.
The results show that the South's growth was broader than a simple retirement story: it included children, young adults, working-age groups and older residents, with the strongest geographic momentum around the outer edges of metro areas.