Ex-Patriotion

With all the talk of late about people choosing to leave the country if one or another presidential candidate wins in November, I got thinking about what it would take for someone to make that choice.  

Apart from those who leave to escape the law or hide assets in Aruba, what would cause a person to become an ex-pat? (if anything)  I wonder if any non-Jewish Germans left their country in the late 1930's when it became obvious that Hitler was taking the country to war for reasons of conquest or opposition to his policy toward the country's Jewish population?  

In this county would it be the arresting of all people of the Muslim faith (as suggested by one candidate)?  Would it be the policy of torturing POW's or killing of the families of suspected terrorists?  Would it be a sense that the country is following an immoral domestic program, or the suppression of the Constitution to allow for dictatorial powers by an executive?

In the 1960's and 70's countless young men left due to the conduct of a war, but many did so to escape the military draft, even thou some left for reason of moral opposition to an unjust war.

During the era of Jim Crow and the early civil rights campaign, people did not leave to oppose our racial relations issues.  People in the south did not leave over the wide-spread lynching of black Americans.  So what would it take for some people to move to Canada or Ireland?
Update Aug 29, 2016.  The number of Americans living abroad (nonmilitary US citizens) estimate to be 8.7 million.  In 1999 there were 4 million.  Accuracy may be in doubt.