The consequences of the building of the transcontinental railroad were many and varied — but on no one was the impact greater than the Plains Indians, who lost both their food supply and their land. Though the buffalo was extinct east of the Mississippi by 1860, there were still two great herds on the Plains, totaling perhaps 15 million. With the building of the Union Pacific Railroad, white hunters began supplying buffalo meat to railroad construction gangs. Beginning in the 1870s, buffalo were also killed for their tongues, prized as a delicacy, and shot for sport from trains. After a market developed for buffalo hides, hunters engaged in systematic and wholesale slaughter. By 1883 the southern herd had been exterminated and a scientific expedition could find only 200 survivors of the northern herd.

The railroads, having contributed inadvertently to the buffalo’s demise, played a more deliberate role in colonizing the Great Plains. Having millions of acres for sale and seeing in settlement the means of generating rail traffic, the railroad companies spent lavishly on attempts to attract settlers from the eastern states and Europe. As well as distributing millions of items of promotional literature, they held out such inducements as credit sales, free “land-exploring” tickets and even temporary accommodations — all of which were remarkably effective.

The idea of a transcontinental railroad attracted increasing public enthusiasm after the California gold rush of 1849. But sectional rivalries prevented any action until 1862, when Congress made lavish land grants to two railroad companies, the Union Pacific and the Central Pacific, to enable them respectively to build westward across the Great Plains from Omaha, and eastward over the Rockies from Sacramento. The Act was a tremendous spur to construction, but there were daunting logistical problems to be overcome. Everything required — ties, stone, rails, rolling-stock, machinery — had to be hauled over long distances. Equally serious was the shortage of labor. Union Pacific construction crews consisted chiefly of Irish immigrants, who sometimes had to exchange their picks for rifles in order to fight off Indian attacks. The Central Pacific relied mainly on imported Chinese laborers who had to blast tunnels through the High Sierras using recently developed nitro-glycerine, which killed many of them. Tracklaying in rugged terrain and extremes of weather averaged only 2-1/2 miles a day, but on May 10, 1869 the two lines met at Promontory Point, Utah, where a final symbolic golden spike was driven into place. Both tracks had soon to be extensively reconstructed, but the completion of the first transcontinental railroad was a remarkable feat, news of which triggered celebrations across the nation.