The first statistics I lead with in my work is that anywhere between 40-60% of ALL Americans move to a new home every 5 years. The housing crisis reduced this a bit, but not by much. This book you mention only provides one narrow view of population dynamics in rural areas - outmigration with harrowing implications that somehow the town is killing itself by 'allowing' and 'encouraging' the kids to leave (none of this is substantiated as they are not doing any sort of long-term analysis). This is not a new phenomena whatsoever, nor is it distinctly rural. I have led research on what I call the "rural brain gain" nationally which shows, yes, 18-25 year olds aggregate themselves in metro areas, that 30-50 year old move to rural communities. Just 1/3 of these "newcomers" are from that small town leaving a full 2/3 never having sustained engagement in that region.

Btw, the term "brain drain" is quite misapplied by most American rural researchers. For some reason, here, we use it to describe HIGH SCHOOL kids leaving. I would be laughed out of any migration conference if I were to call that a brain drain. Internationally, they use the term to describe the loss of the best an brightest - Ph. D. doctors, engineers, etc. from India/China/Africa - to the United States!

So in our rural communities, one one hand we lost 18-22 year olds with little to no education, experience, etc. and on the other hand we bring in 30-50 year olds who have all that and more. Crazy and frustrating. For me, it's just another negative narrative about Rural America that is based on stereotypical understanding of a bygone rural. Rural is much more diverse and complex than ever before - less than 5% of rural Americans have anything to do with agriculture anymore but this message is lost when we talk about the Farm Bill being the savior of rural Americans.