The Scots-Irish (lowland Scots who immigrated to the US from Northern Ireland) settled thickly in the South. Even Mississippi.
You can see how the storms in Europe washed up a lot of treasure on the shores of this country.
Napoleon needs money to finance his conquests? He sells off the French holdings in the New World. Voila! Louisiana Purchase. That empire tries to recover some of its lost ground? Maximillian is made emperor of Mexico. The French are defeated? Maximillian's head rolls.
James I suppresses the Puritan "Roundheads"? Separatists move first to Holland, then finally to the New World. Bingo! Plymouth Rock! A czar needs troops to fight off Napoleon's expansionist dreams? A bunch of German expatriates leave Odessa and Belorussia and move to North and South Dakota.
One of the reasons I love history. It's alive everywhere around you.