Between 1800 and 1920 Ireland was the most emigration-prone of all European countries. Political and religious repression under British rule, rapid population growth, periodic famines, and the absence of domestic industrialization prompted approximately eight million Irish women and men to seek a better life abroad. Before the Great Famine of the 1840s, Canada was a favored destination of this exodus, while the majority of postfamine emigrants were attracted to the United States. When the Great Plains of both countries was opened up after about 1860, it was not surprising that the Irish, with their long tradition of migration in search of economic opportunities, were conspicuous agents in the westward spread of white settlement. Like many other newcomers, the Irish sought to mitigate the dislocation of transatlantic mobility by transplanting core elements of their traditional culture to their new environment. Consequently, the settler societies that emerged in the Great Plains north and south of the forty-ninth parallel owed much to the traditions, institutions, and ideological orientations of the Irish.

The agricultural potential of the Canadian Prairies was first noted by Capt. John Palliser in 1857, and over the next decades fellow Irishmen Millington Synge, John Macoun, and Clifford Sifton worked to promote the settlement of the region. When the initial pioneer phase was completed in 1911 the Irish were a significant element within the emerging provincial mosaics. Almost 160,000 people, comprising 13.1 percent of the population of Manitoba, 12.2 percent of Saskatchewan, and 10.9 percent of Alberta, were of Irish ethnicity. Approximately 10 percent of these were Irishborn, but the majority.more than 65 percent. were the descendants of earlier Irish emigrants to eastern Canada, with Ontario being the largest source. The remainder came from the United States. Although spread across a range of occupational categories, the Irish who migrated to the Canadian Prairies were motivated primarily by the desire to own land. In 1911 more than two-thirds lived in rural areas and were either homesteaders or farm laborers working to accumulate the resources necessary to begin homesteading.

As with the larger Canadian Irish population, Protestants outnumbered Catholics by a margin of two to one among the western Irish, and typical also was their respective attachment to two peculiarly Irish institutions—the Orange Order and the English-speaking Roman Catholic Church. Both of these had evolved over centuries in the homeland as expressions of Irish Protestant and Catholic cultures, and they subsequently became vehicles for the intergenerational transmission of these two Irish identities throughout the diaspora. Because of their early arrival on the Prairies, these institutions became forums for integrating the Irish with other nationalities, promoting social cohesion in ethnically diverse frontier societies. Although frequently at loggerheads with each other on sectarian grounds, the Protestant and Catholic Irish were nevertheless in agreement on the desirability of cultural conformity and the primacy of the English language in the creation of a new western Canadian identity.

The experiences of the Irish who settled in the American Great Plains were even more varied than those of their counterparts north of the border. As early as the 1820s Irish lumbermen were following the timber trade west through Illinois, Michigan, and Wisconsin, and by the 1860s significant numbers of Irish families were homesteading in Nebraska, Kansas, and Texas. Railroad construction, on the Kansas Pacific for example, brought more Irish to the Plains, and others came with the military. Eventually, Irish founded such Plains towns as Garryowen, South Dakota, O'Neill, Nebraska, and Chapman, Kansas, and there was a major Irish immigrant presence in such cities as Denver and Omaha. In Omaha, for example, in 1880, Irish occupied 44 percent of the city's blocks, with a concentration around the Union Pacific rail yards.

The vast majority of the Irish who settled in the American Plains were Roman Catholics who came directly from Ireland, and the Church remained central to their communal lives. The fate of the homeland was also an abiding concern. Thus, radical Irish nationalist organizations found strong support among Irish Americans in the Plains, and these served to promote both Irish particularism and working-class militancy. Because of their numbers and organizational cohesion, the Irish became a dominant force in local politics at the turn of the century, and this brokerage position allowed them to act as Americanizers of other European ethnic groups that subsequently migrated west.

An analysis of Irish settlement in the Great Plains suggests that the popular stereotype of eastern urbanization and ghettoization represents only one dimension of the North American Irish diaspora. Although anti-Irish prejudice lingered as a structural barrier, especially in the United States, the Irish nevertheless possessed certain advantages. Early arrival, white skin, Christian adherence, proficiency in the English language, familiarity with the democratic process, and the ability to exploit a wide range of economic opportunities all presaged success. Thus, the Irish must be viewed as central agents in the massive continental transformation represented by the creation of white, Christian, commercial settler societies in the Canadian and American Great Plains during the second half of the nineteenth century.