New federal population figures out Thursday show the nation’s youngest county is in the Northwest. And it’s not in an urban area. Madison County, Idaho, is in the midst of eastern Idaho's potato country.
To give a comparison, the median age of the United States is almost 38 years old. The median age of Madison County is 23. That’s the lowest in the country and there’s one big reason: Madison County is home to Brigham Young University-Idaho.
College students like Matt Urick are considered part of a county’s population if they live there most of the time. And the 13,000 -student Mormon school has an outsized influence on this 37,400-person county near the Teton mountains.
But there’s something else. More than one out of four BYU-Idaho students is married. And many of those students have started having children.
“Any time my wife and I go out to eat, there’s kids all the time," Urick said. "Whether they’re at the table next to you or whenever we go do anything in the community -- people hike with their kids. Yeah, this place is crawling with kids.”
Seventy percent of the population in Madison County is under the age of 30. That’s high even compared with other counties with university towns. In Latah County, home to the University of Idaho, 52 percent of the population is under 30.
And youth has its benefits. Madison County is the healthiest county in Idaho, according to a ranking by the Robert Wood Johnson Foundation. But it also ranks high in poverty counts because college students don’t have much income.
The Madison School District's Janet Goodliffe said all those kids have given the schools a surge in enrollment. She said the shift started happening in 2001, when Ricks College in Rexburg became BYU-Idaho and expanded to a four-year school.
“You see new schools being built, new facilities needed," Goodliffe said. "We’ve built a new high school, two new elementary schools.”
But even the nation’s youngest county is getting older like the rest of the U.S. Though just barely. Between 2010 and 2013, Madison County’s median age increased by half a percentage point.
Statewide, the median age in Idaho ticked up slightly to 35.5. Washington crept up to 37.5 and Oregon to 39.
The figures are part of new estimates the Census Bureau released Thursday that examined population changes between April 1, 2010, and July 1, 2013.