The aging of the American population is a decidedly different story from region to region.

According to the 2010 census, the greatest share of young people live in the West while the largest proportion of older Americans reside in the Northeast.

Among the nation’s 309 million people, Maine, Vermont, West Virginia, New Hampshire, Florida, Connecticut and Pennsylvania had the oldest populations, with a median age older than 40.

On the other end of the spectrum, Utah, Texas, Alaska and Idaho ranked as the youngest, with a median age younger than 35. In an exception to the rule, the District of Columbia also fell into this group, with a median age of 33.8.

Since the previous census in 2000, Maine and Vermont surpassed West Virginia and Florida as the states with the highest proportion of residents older than 65. Florida and West Virginia remain the states with the highest number of older Americans, however.

Maine had the country’s highest median age at 42.7 years, well ahead of second-place Vermont at 41.5. Utah was the youngest, at 29.2, far lower than the 33.6 median age in Texas.

The broader regional differences were just as stark and may represent challenges for policy planners if the broad population trends drive conflicts in choices. The Northeast, for instance, measured 14.1 percent of its population older than 65 in 2010; the West counted just 11.9 percent.

“In the four census regions, the region with the oldest median age was the Northeast (39.2), followed by the Midwest (37.7), the South (37), and the West (35.6),” the Census Bureau said in a 2010 report on age and sex composition.

Over 10 years, the median age nationally rose from 35.3 to 37.2. It was 28.1 years in 1970.