Research papers on Irish Immigration show that the main sweep of Irish immigration consisted of 1.5 million Irish who fled famine conditions and arrived between 1845 and 1854. They initially thought of themselves in 'peasant' terms: they identified themselves in terms of their families, villages, parishes, and perhaps counties. Forced into urban centers with Irish people from every town, parish, and county, however, the immigrants soon began to lose their old modes of identity. This process was accelerated as nativist hatred and common living conditions forced the immigrants to think of themselves as a single community.
Different from the Irish, the Scotch-Irish emigrated to America for several reasons, the most important being economic. Conditions turned bad for most of them in Northern Ireland (also called Ulster) around the turn of the 18th century when land rents went up sharply and it became increasingly difficult for small farmers to support a family. Since the Scotch- Irish were Calvinist Presbyterians they also under new British laws that deprived non-Church of England "dissenters" of political rights.
Yet, perhaps because they had to struggle so hard to exist on marginal lands and because they lacked the educational or social polish of immigrants from England, the Scotch-Irish have seldom been portrayed in a flattering way. Travelers on the American frontier often reported on the eccentricities of these isolated people, and repeated political conflicts with colonial governments over land and taxes created the impression that they were uncouth and undisciplined. The 20th-century stereotype of the "hillbilly" developed directly from these 18th-century beginnings.Paper Masters