The famine migration, the massive Irish immigration of the mid-nineteenth century, was over well before 1880; however, the Irish continued to immigrate in great numbers for decades after the famine years. The number of later arrivals was never as great in any one decade as it had been in 1845–55, but impressive numbers arrived in every decade thereafter. By 1900, a majority of Irish immigrants living in the United States had arrived after the famine years. About 1.9 million had come between 1830 and 1860, and another 1.9 million arrived between 1860 and the turn of the century. Nearly three-quarters of a million more came between 1900 and the Great Depression. The American descendants of these immigrants probably number well over 15 million today. The coming of the Irish is a major theme in American history, a long, often painful process of accommodation by immigrants and their children and grandchildren–a theme not merely of one era but of successive eras.

Many studies of Irish-American communities in the late nineteenth and early twentieth centuries have appeared recently. These have stressed, first, that the concentration on the northeastern states in earlier histories was misplaced; the Irish, particularly after the famine migration years, settled throughout the country. Moreover, those who settled outside the Northeast may have fared better economically than the rest. Finally, these recent studies have stressed that most earlier historical work concentrated on the famine migration and ignored the social accommodation of later generations.