Minnesota gained more than 32,000 residents this year, bringing the state's population to an all-time high of 5,489,594, new U.S. Census Bureau estimates say.

But the state's population gains may be showing signs of the slower growth expected to shape Minnesota's future.

The modest 0.6 percent year-over-year growth rate put Minnesota at No. 24 nationally, well below the state's oil-rich neighbor. North Dakota remains the country's fastest growing state. Its population grew just over 2 percent as its oil fields continue drawing workers, even as the boom fades.

Iowa ranked 28 for growth, Wisconsin came in at 38th. Seven states lost population, with West Virginia posting the largest declines.

The U.S. Census Bureau measures state population change from July 1 to July 1 each year.

Minnesota has been adding residents at just under 1 percent for years. Still, the 0.6 percent growth for 2015 is down slightly from previous years. In 2013, for instance, the population grew 0.7 percent.

It's a minute change that state demographer Susan Brower is watching, because she anticipates smaller and smaller annual growth rates as baby boomers age, people have fewer children and the state continues to see more people moving out of Minnesota than are moving in from other states.

U.S. state population change, 2010-2015

Source: U.S. Census Bureau. Map by C.J. Sinner

Brower projects Minnesota's population growth to slow to 0.3 percent in the late 2030s.

The slowing growth is a long-term concern for Minnesota's employers, some of whom are already reporting difficulty finding workers. The state's unemployment rate now stands at an adjusted 3.5 percent, the lowest since early 2001.

"It tees up this situation for prolonged labor force shortages if we don't see some turnaround in migration," Brower said.

Minnesota's growth is fueled largely by natural increases — more births than deaths — and the flow of immigrants from abroad, which helps replace the people who leave Minnesota for other states. In the most recent year, Minnesota lost about 12,000 more people to other states than it gained, but it made up for that by gaining 15,000 people from abroad.

"That really kinds of saves us in terms of migration," she said.

Brower says she keeps a close watch on the migration numbers, which will play a greater role as the state's population ages.

"We're moving closer and closer to time when it will be harder and harder to grow from births alone," she said.

Jennifer Bjorhus • 612-673-4683
MaryJo Webster • 612-673-1789