The median age in the United States rose by 2.7% between 2010 and 2018, rising from 37.2 years to 38.2 years, according to the Census Bureau's 2018 Population Estimates. Maine had the highest median age at 44.9 years; Utah had the lowest at 31.0 years. North Dakota was the only state to see a decline in its median age, from 37.0 years in 2010 to 35.2 in 2018. At the county level, 81.7% of the nation’s 3,142 counties had a higher median age in 2018 than in 2010. About . . .