The United States has historically been a place of great mobility — when local economies have lost hope, Americans have often picked up and moved to where the jobs were.

This time seems different: Americans have not abandoned the rust belt towns of Michigan, Wisconsin and elsewhere in droves as jobs have fled (see chart below), and some say they should. But MIT economist Daron Acemoglu disagrees: migration is too disruptive to families and the cities that workers leave. In an interview with Axios, he said policymakers shouldn't encourage them to go.

Data: Census Bureau, Current Population Survey; Chart: Andrew Witherspoon / Axios Acemoglu said:"Migration puts a lot of negative pressure on the families that migrate, who have to go and adapt with low income to an entirely different area."It can leave an economic "wasteland" in the wake of fleeing workers.In Detroit, housing prices and tax revenues have plunged, and it can no longer provide adequate schooling or other public services for those who remain.And while economists see the benefits of the historic readiness of U.S. workers to relocate, they say migration may not be the silver bullet it once was. Economic historian Robert James has written that current workers must have "skills and initiative" if they are to successfully migrate, unlike past great migrations in which just showing up was often sufficient to find a job. He argues, "In today's world, workers must learn to embrace adaptability and flexibility. ... Unfortunately, the U.S. and most other industrialized countries, with their stultifying and rigid education systems, have failed to prepare people for this reality."