The large and continuing emigration from Ulster led to the term "Scotch-Irish" being used in the American colonies starting in the early 18th century to distinguish Ulster Presbyterians from other British and Irish immigrants. Scotch-Irish immigrants formed a majority of all European migration to America from 1717 until the 1770s, and by the time of the American Revolutionary War, they were the largest European ethnic group in the thirteen colonies.
The migration of Scotch-Irish to the Americas continued at a high level until about the 1770s, when it declined because of the outbreak of the American Revolutionary War. By that time, an estimated 200,000 Scotch-Irish had settled in the American colonies, making up about one-third of the total European population. They played a major role in the development of the American colonies and were especially important in the backcountry frontier regions. Scotch-Irish communities were established throughout the colonies, particularly in the Appalachian Mountains and the Piedmont region.
The Scotch-Irish were also very active in the American Revolution, and they provided many of the soldiers and leaders who fought for American independence. Some of the most famous Scotch-Irish include Andrew Jackson, Henry Clay, and John C. Calhoun. After the war, the Scotch-Irish continued to play a prominent role in American society and politics. They have made important contributions to all aspects of American life, including business, industry, education, and culture.