I've mostly given up on trying to counter all the myths that pass for truth in these parts-many of which have to do with losing people, brain drain etc...
Richard Florida has a good post and map at The Atlantic showing the percent of people living in the state they were born in. Surprise, Pennsylvania, Ohio, Michigan, West Virginia and several other "rust belt" states lead the nation.
Is that a good thing? 70% or more of the people in these states were born in state, yet this is mostly a list of the nation's economic laggards. What should be pretty obvious, is that fairly high numbers of people moving both in and out, correlates pretty strongly with economic growth, with most of the states with healthy economies falling closer to the middle in this category.
Florida guesses that the recent dramatic declines in mobility, don't bode well for the economy. What's so disturbing is that in 80% of the region this isn't even widely recognised as a problem.
Several good reads on this subject.
The Geography of Stuck
America The Stuck
Burgh Diaspora is a blog that mostly focuses on the general subject.