(NewsNation) — Nearly half of the cities in the United States could see declines in their populations by the year 2100, leading to some grim consequences, a new study shows.

University of Illinois Chicago researchers, using population projections, found that some cities could see a depopulation of as much as 12 to 23%.

Such a decline could bring unprecedented challenges to communities when they try to provide or maintain basic services like transit, electricity and even clean water.

Ellen Dunham-Jones, a professor at the Georgia Institute of Technology, says this issue isn’t new: Many cities, especially smaller towns in rural areas, are losing people.

What’s happening is a migration out of rural areas toward the suburbs, where Dunham-Jones says many jobs are.

“When you have a declining population, that means you have less tax base to support all of the infrastructure,” Dunham-Jones said.