The South was the only region of the United States to add children over the past five years, bucking a nationwide decline in the population under age 18 as the Northeast, Midwest and West all saw their share of young residents shrink, according to new U.S. Census Bureau estimates released Thursday.

Between 2020 and 2025, the South gained nearly 304,000 residents under 18, an increase of about 1.1%, while the nation's child population fell by roughly 1.8 million, or 2.4%, the Census Bureau said in its Vintage 2025 population estimates.

The West recorded the steepest decline in its youth population, losing more than 1 million children, or 5.7%, over the five-year period. The Northeast's under-18 population fell 4.1%, while the Midwest posted a 3.9% decline.

The findings underscore the South's continued demographic dominance, fueled by strong domestic migration and population growth that has made it the nation's fastest-growing region since 2020. The Census Bureau said the South was the only region to record growth across all five major age groups it tracks, from children to older adults.

"Many counties across the country saw slower growth in the past year, but those in the South were less affected," the agency said.

Much of the South's increase occurred in counties surrounding major metropolitan areas, where expanding suburbs attracted families and working-age adults. Those outlying metro counties more than offset child population losses in smaller cities and rural communities across the region.

Nationally, the data point to an aging population. While the number of children declined, older age groups continued to grow, reflecting lower birth rates and the aging of the large baby boomer generation.

The Census Bureau's estimates also showed population growth varied sharply by geography. Southern counties continued to dominate the list of the nation's fastest-growing counties, a trend that has persisted since 2020.

The regional divide could have long-term implications for schools, housing, transportation and political representation. States and communities across the Northeast, Midwest and much of the West may face declining school enrollments and fewer young families, while rapidly growing parts of the South could experience increased demand for classrooms, infrastructure and public services.

The estimates are part of the Census Bureau's annual Vintage 2025 population series, which measures demographic change between April 1, 2020, and July 1, 2025. The data incorporate births, deaths and migration to estimate population changes for counties and regions across the country.