It was not until the period following World War II , however , that Appalachians became one of the major population groups in these metropolitan centers .
People have been migrating from Appalachia to cities outside the region ever since many of these cities were founded .
It was not until the period following World War II , however , that Appalachia became one of the major population groups in these metropolitan centers .
People have been migrating from Appalachia to cities outside the region ever since many of these cities were founded .