Irish immigration to America is generally divided into two periods: before 1846 it was primarily Scots-Irish Protestant, while after 1846 it was predominantly Catholic. This guide concentrates on the Irish Catholic diaspora who came during the 19th century Irish famine. The failure of the 1845 potato crop prompted hundreds of thousands to emigrate to North America. Fleeing famine, these immigrants were often poor and destitute. Facing widespread discrimination in America ("Irish need not apply"), they formed immigrant communities in cities along the northeastern seaboard, as well as immigrant communities outside the cities, especially in the Midwest, where they provided cheap labor building canals, railroads, other infrastructure projects, and in the mining and quarrying industries. They also volunteered in large numbers to fight in the Civil War, after which they gradually became more widely accepted in America.