June 21 (UPI) -- The non-Hispanic white population was the only ethnic group in the United States to decrease in size between 2016 and 2017, the U.S. Census Bureau said Thursday.
In a new report, the Census Bureau found the U.S. population has become more racially and ethnically diverse. The country's Hispanic population increased by 2.1 percent to 58.9 million between 2016 and 2017 and the Asian-American population -- the nation's fastest-growing racial group -- increased by 3.1 percent to 22.2 million during that time.
Meanwhile, the non-Hispanic white population decreased by .02 percent to 197.8 million, the bureau said.
"White fertility has gone down. There's a little bit less white immigration in the last year," William Frey, a demographer and sociologist at the Brookings Institution in Washington, told The Hill. "As the white population becomes older, that means that even if fertility gets up a little bit, it's not going to be what it was a long time ago."
Among U.S. states, California had the largest Hispanic and Asian-American populations. The bureau noted Hawaii was the only state with a majority Asian-American population. Cook County, Illinois, which includes Chicago, had the largest black population of any U.S. county at 1.3 million, the bureau determined.
As the U.S. population diversifies, it also is aging, the bureau said.
Populations in most U.S. counties continued to grow older and the nation's population as a whole experienced a median age increase from 37.2 years to 38.0 years from 2010 to 2017.
"Baby boomers, and millennials alike, are responsible for this trend in increased aging," Molly Cromwell, a demographer at the U.S. Census Bureau, said in a statement. "Boomers continue to age and are slowly outnumbering children as the birth rate has declined steadily over the last decade."
Florida's population had the highest rate of seniors -- those ages 65 and older -- at 20.1 percent. The state was followed by Maine at 19.9 percent and West Virginia at 19.4 percent.
Midwestern areas generally led the way among the 531 U.S. counties that got younger between April 2010 and July 2017, the report said.
"The majority of the counties getting younger were in the Midwest, and of these counties with 10,000 people or more in July 2017, some of the largest decreases were in North Dakota, South Dakota and Nebraska," Cromwell said.