Comment by _DeadFred_

The American heartland has been hollowed out. Almost all of mom's generation of family (cousins, distant cousins, etc) left Iowa. That left few in her generation to have new Iowans, and those few raised/taught their kids to stay in Iowa because farms, family, whatever their motivation for staying was. Lots of the remaining country folk are country for religious reasons and again aren't super likely to move (though they have started starting new religious colonies around the country).