The Atlantic magazine has ripped the Band-Aid off a disturbing social trend, what it calls “the disappearance of children under five in progressive cities.”

In all urban counties, the population of children under five years old fell by 8 percent; it fell by 18 percent in New York City and by 5 percent nationwide.

Liberal writer Derek Thompson puts it bluntly: “I must admit that progressives do have a family problem… in large urban metros, the number of children under 5 years old are in a free fall. Several counties–including those encompassing Manhattan, Brooklyn, Chicago, Los Angeles, and San Francisco—are on pace to lose 50 percent of their under-5 population in 20 years.”

“I’m deeply worried about a family-exodus doom loop,” says Connor O’Brien, a policy analyst at the think tank Economic Innovation Group, says.  “When the population of young kids in a city falls 10 or 20 percent in just a few years, that’s a potential political earthquake.”

The top two reasons for parents leaving the “progressive” inner cities are crime and schools. The best way to bring families back to the cities is school choice – but the unions won’t allow it. We wonder if there will still be teacher unions in cities, when there aren’t any kids to teach.