Migration
From 1710 to 1775, over 200,000 people emigrated from Ulster to the original thirteen American colonies. The largest numbers went to Pennsylvania. From that base some went south into Virginia, the Carolinas and across the South, with a large concentration in the Appalachian region; others headed west to western Pennsylvania, Ohio, Indiana, and the Midwest.
Transatlantic flows were halted by the American Revolution, but resumed after 1783, with total of 100,000 arriving in America between 1783 and 1812. By that point few were young servants and more were mature craftsmen and they settled in industrial centers, including Pittsburgh, Philadelphia and New York, where many became skilled workers, foremen and entrepreneurs as the Industrial Revolution took off in the U.S. Another half million came to American 1815 to 1845; another 900,000 came in 1851-99. From 1900 to 1930 the average was about 5,000 to 10,000 a year. Relatively few came after 1930. At every stage a majority were Presbyterians, and that religion decisively shaped Scotch-Irish culture.
According to the Harvard Encyclopedia of American Ethnic Groups, there were 400,000 U.S. residents of Irish birth or ancestry in 1790 and half of this group was descended from Ulster, and half from the other three provinces of Ireland.
A separate migration brought many to Canada, where they are most numerous in rural Ontario.
Read more about this topic: Scotch-Irish American