Alabama is aging.

No, this isn’t about the state’s recent bicentennial. The median age in Alabama has increased since 2010, according to recently released data from the U.S. Census Bureau. And it’s going up at a faster rate than most of the United States.

In 2010, Alabama was the 24th oldest state in the country, with a median age of 37.8 years. That means half of the people in Alabama were older than 37.8 and half were younger. By 2018, Alabama had climbed the rankings to 18th oldest in the nation, with a median age of 39.3.

That 1.5-year increase is the 15th largest rise in the country.

That’s also older than the nation as a whole. The median age for the United States went up by one year, to reach 37.9 as of 2018.

And some rural parts of Alabama are graying even faster.

In southwest Alabama, Washington County aged the fastest between 2010 and 2018. The median age there went up by 4.2 years during that time, bringing it to 43.6 years. Wilcox County was only slightly behind with a 4.1 year increase since 2010.

Only four counties in Alabama saw their median age decrease between 2010 and 2018. | graphic by Ramsey Archibald

But despite the recent changes, neither Washington nor Wilcox are the oldest county in Alabama. That honor belongs to Coosa County, just south of Talladega. The median age in Coosa County is 46.9 years -- nine years older than the national average.

The three youngest counties in Alabama are all homes to prominent college towns. Tuscaloosa and Lee, home of the University of Alabama and Auburn University, respectively, are both very young compared to the rest of the state. But they aren’t the youngest.

Pike County, home of Troy University, has the lowest median age in the state at just 30.8 years, meaning half of its population is young millennials or even younger. Lee is second at 31.4 years, and Tuscaloosa is third 32.7. There’s a significant jump up to 4th-place Sumter County, which is also the home to college town - Livingston and the University of West Alabama. The median age there is 35.8.

Pike and Sumter counties are among only four counties in Alabama that saw the median age decrease from 2010 to 2018. The others were Franklin and Russell. Franklin County in northwest Alabama has seen an influx of younger residents through immigration in recent years. Russell County on the Georgia line is near a military base.

Coosa County is the oldest county in Alabama in terms of median age. | Graphic by Ramsey Archibald

Among the state’s four largest counties, Jefferson County, home to Birmingham, had the smallest age increase at just 0.7 years. The median age in Jefferson in 2018 was 37.7 years, younger than both Alabama and the U.S medians.

But it isn’t the youngest of the four largest counties in the state.

Both Mobile and Montgomery counties are younger than Jefferson. Montgomery has the lowest median age at 36.2 years, while Mobile sits at 37.6. Both are rising faster than Jefferson, however. Mobile’s median age increased by 1.3 years between 2010 and 2018, while Montgomery’s increased by 1.6 years.

Madison County, home to Huntsville, is the oldest of the big four at 38.5 years, and saw a 1.4-year increase in median age since 2010.

Do you have an idea for a data story about Alabama? Email Ramsey Archibald at rarchibald@al.com, and follow him on Twitter @RamseyArchibald.