While the greatest concentrations of Irish Catholics in America remained eastern-based and urban, they would contribute significantly to the settlement of the American West. The 1849 Gold Rush attracted a substantial Irish influx to California: by 1880 37 per cent of the population of San Francisco was Irish. In the 1860s, the Union Pacific Railroad was overwhelmingly constructed by Irish labour. The railhead, Omaha in Nebraska, had a 44 per cent Irish population by 1880. Another significant factor in dispersal was military service. Almost 150,000 Irish served in the Union Army in the Civil War, and the Irish featured prominently in the military pacification of the West. Irish lumberjacks steadily migrated west, following the timber and reaching Oregon and Washington in the 1870s. From the 1860s a steady flow of westward bound Irish homesteaders developed, seeking land, and fleeing poverty and the anti-immigrant discrimination of the ‘Know Nothing’ political movement.
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