Under-18 population in U.S. declined by 1 million over last decade

• The U.S. is also becoming more diverse, more urbanized and growing slower overall than in past decades, Axios' Stef Kight reports.

By the numbers: The Census Bureau tallied 73.1 million people who were younger than 18 years, a 1.4% decrease from the 74.2 million counted in 2010.

• 258.3 million people — 77.9% of the country's total population — were 18 years or older, which was a 10.1% increase from the 2010 census.

The big picture: Proportionally, there are more people under the age of 18 living in the South than any other region of the U.S.

• Southern states in total reported the highest proportion of people under age 18 (22.5%) to adults (77.5%) and were the only part of the country to experience a growth in both age groups over the last decade.
• The Northeast had the largest proportion of adults (79.7%) and the smallest proportion of people under age 18 (20.3%).

Go deeper: 2020 census has unusually high rate of unanswered questions