Census estimates show the U.S. growing older as the South gains ground

New Census Bureau estimates show the United States aging quickly, with growth since 2020 concentrated among older adults and in the South. Fortune reported that the shift carries economic and political stakes because younger and midlife age groups are shrinking or barely growing across much of the country.

The Census Bureau’s Vintage 2025 population estimates put the median age in the U.S. at 39.4 as of July 2025, up from 38.6 five years earlier. The agency’s figures show the population grew unevenly by age, with Americans 65 and older increasing far faster than every younger group.

From April 2020 to July 2025, the 65-and-older population rose 16.2%, according to the Census Bureau data cited by Fortune. The 25-to-44 group, broadly aligned with millennials, grew 5.9%, while the 18-to-24 group increased 2.1%.

Children and midlife adults moved in the other direction. The under-18 population fell 2.4%, and the 45-to-64 group declined 3.2%, according to the same Census estimates.

The South stands apart

The Census Bureau figures show the South was the only region to post growth in all five age groups tracked: children, young adults, adults ages 25 to 44, adults ages 45 to 64, and people 65 and older. The region’s total population increased 6% over the period, compared with 3.1% nationally, Fortune reported.

In the South, the under-18 population grew 1.1%, and the 45-to-64 group edged up 0.1%, or about 19,000 people, according to Fortune’s reading of the Census data. Other regions lost population in at least two age categories.

The Northeast lost 4.1% of its under-18 population and 7.1% of its 45-to-64 population, according to the Census figures cited by Fortune. The Midwest’s child population declined 3.9%, while its 45-to-64 group fell 6.2%. The West recorded a 5.7% drop in children, the steepest such decline among the regions.

Lauren Bowers, chief of the Census Bureau’s Population Estimates branch, said several forces are changing regional age patterns. “The continued transition of baby boomers into retirement age, compounded by local migration and fertility patterns, is shifting the demographic makeup of the country,” Bowers said.

Generational effects

Fortune framed the data as evidence of a demographic imbalance led by the size and longevity of the baby boom generation. The report noted that baby boomers own about one-third of the nation’s housing stock, citing a Realtor.com report based on National Association of Home Builders analysis, and remain the largest share of home buyers, citing the National Association of Realtors.

Gen X, born roughly from 1965 to 1980, lines up closely with the Census Bureau’s 45-to-64 category, Fortune reported. That bracket declined in the Northeast, Midwest and West, while the South posted only a fractional gain.

Fortune also cited University of New Hampshire Extension data putting Gen X at about 65 million people, smaller than both baby boomers and millennials. Pew Research Center has described Gen X as America’s overlooked “middle child,” a label Fortune used to explain the generation’s limited weight in demographic measures.

Millennials, roughly represented by the 25-to-44 age bracket, grew fastest in the South, according to the Census data cited by Fortune. Bowers said growth in the South from 2020 to 2025 was especially visible in outlying counties of metro areas, which “grew the fastest across all age groups, and often by a large margin.”

Fortune reported that those outlying counties include exurban areas around cities such as Atlanta, Charlotte, Dallas and Nashville. The Census data does not assign a single cause for that pattern, but Bowers pointed to migration, fertility and the aging of baby boomers as key factors behind the country’s changing age profile.

This story draws on original reporting from Fortune.