The median age in most areas of the US is rising, while the population is growing more diverse, according to Census Bureau data released Thursday. America’s median age - the age where half of the population is half younger and half older - rose from 35.3 years on April 1, 2000, to 37.9 years on July 1, 2016, according to the data. Meanwhile, the population of White Americans is growing at a much slower rate than most minority groups: The number of whites living in the US increased by 0.5% last year to 256 million. By comparison, the Asian population grew 3% to 21.4 million, the black or African American population grew by 1.2% to 46.8 million and the Hispanic population grew 2% to 57.5 million.

The US isn’t the only country struggling with an aging population. With average marriage ages rising, and economic circumstances making it more difficult for couples in developed economies like the US, Japan and Europe to afford children, many countries are facing a demographic crunch in social welfare programs. But nowhere is this more of an immediate problem than China, where – thanks to its decades-long one-child policy – the working-age population will soon fall off a cliff.

[Source: U.S. Census Bureau]

In the US, the baby-boom generation is largely responsible for this trend, according to Peter Borsella, a demographer in the Census Bureau’s Population Division. “Baby boomers began turning 65 in 2011 and will continue to do so for many years to come.”

Indeed, the number of US residents aged 65 and over grew from 35 million in 2000, to 49.2 million in 2016, accounting for 12.4 percent and 15.2 percent of the total population, respectively.

With growth rates for white Americans expected to remain subdued, the Associated Press says they will cease being the majority ethnic group some time after 2040, though they will remain a plurality of the population.

The youngest cohort of America's population is also one of its fastest-growing: The Census report showed that children in the US born from 2001 through 2016 were the nation's fastest-growing age group, with a 6.8 percent jump in the year beginning July 1, 2015.

Putting its own spin on the census data, The New York Times compared each of the US’s 3,000 counties with the national population at different points in America's history - as well as its future. The Times found that counties with populations that are about 75 percent white tend to reflect the America of the 1970s and 1980s. Those where the population is half white and more diverse tend to reflect the (projected) America of the 2040s and 2050s.

For example, Sioux Falls, South Dakota, which is 84% White, resembles America in 1989. Meanwhile, Tooele County, in Northwestern Utah, more closely resembles America from 1971, when the population was both less diverse and younger. Seminole County, near Orlando, Fla., most closely matches the nation’s current mix, followed by Richmond County, aka Staten Island, in New York City.

Urban counties, which tend to be more diverse than suburban or exurban areas, more closely resemble the America of the future. Cook County, Ill., closely resembles what demographers believe the US will be like in 2047. Maricopa County, Ariz., resembles the demographics of the nation in 2020.