Census: 2 Utah counties are among the youngest in the nation

The big picture: Utah's youthfulness can be attributed to the state's high fertility rate and people under age 18 making up about 28% of the state population.

• About half the state's population is younger than 31.

Zoom in: Utah and Cache counties were among seven counties in the nation with a population of at least 100,000 that had a median age of under 30.

• The median age in Utah County, home to two major universities, — UVU and BYU — is 25.7. It's 25.8 in Cache County.