Much of what follows is based on a column written by Yoni Appelbaum in The New York Times:

The idea that people should be able to choose their own communities — instead of being stuck where they are born — is a distinctly American innovation.  It is the foundation for the country’s prosperity and democracy, and it just may be America’s most profound contribution to the world.

We are a migratory people and we flourish best when we make the occasional change of base.

Entrepreneurship, innovation, growth, social equality — the most appealing features of the young republic — all can be traced back to this single, foundational fact:  Americans were always looking ahead to their next beginning — always seeking to move up by moving on.

But over the last 50 years, Americans have stopped moving, and this is the single most important social change in that time.  Every social ill you can spot in America today — as well as the election of Donald Trump to the presidency twice — can be traced to America’s loss of mobility.