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.