In this July 3, 2017 file photo, a man and woman walk under trees down a path at Alta Plaza Park in San Francisco. Data from the U.S. Census Bureau shows the median age in the U.S has increased by a year to 38.2 years from 2010 to 2018. The date released Thursday, June 20, 2019, comes as many baby boomers have been hitting the retirement age in recent years. (AP Photo/Jeff Chiu, File)

America is aging.

Data released by the U.S. Census Bureau on Thursday shows the in the U.S. increased by a year to 38.2 years from 2010 to 2018.

If there's someone to blame, it's the baby boomers. Many in that group of Americans born between the end of World War Two and the Beatles' American invasion in 1964 have been hitting the retirement mark in the past eight years.

"This aging is driven in large part by baby boomers crossing over the 65-year-old mark," said Luke Rogers, the chief of the Population Estimates Branch at the Census Bureau.

The gray hairs are showing up faster in some places than others, at least percentage-wise.

In Puerto Rico, the median age jumped by almost 6 years, from 36.9 years to 42.8 years. That was driven by moving to the U.S. mainland after Hurricane Maria caused widespread destruction on the island in 2017.

Among U.S. states, Maine had the greatest increase in median age, 2.2 years, going from 42.7 years to 44.9 years. For several years now, Maine has been ahead of the curve with an , a result of stagnant growth where deaths outnumber births and few people moving in.

The only state whose median age got younger was North Dakota, which has undergone a population boom driven by growth in the energy sector. The median age went from 37 years in 2010 to 35.2 years in 2018.