Immediately after the Civil War the long drives of cattle from Texas to the Kansas railroad head began to cross Oklahoma, traveling over the cattle trails that became part of Western folklore. The best known was the Chisholm Trail. The cattle were fattened on the virgin ranges of Oklahoma, and cattlemen began to look on the grasslands with speculative and covetous eyes.
The first railroad to cross Oklahoma was built between 1870 and 1872, and thereafter it was not possible to keep white settlers out. They came despite proscriptive laws and treaties with the Native Americans, and by the 1880s there was a strong admixture of whites. In addition, ranches were developed that were nominally owned by Native Americans, but actually controlled by white cattlemen and their cowboys. The region quickly took on a tinge of the Old West of the cattle frontier, a tinge that it has never wholly lost.
In the 1880s land-hungry frontier farmers, the boomers, agitated to obtain the “unassigned” lands in the western section—the lands not given to any Native American tribe. The agitation succeeded, and a large strip was opened for settlement in 1889. Prospective settlers lined up on the territorial border, and at high noon they were allowed to cross on a “run” to compete in finding and claiming the best lands. Those who illegally entered ahead of the set time were the nicknamed the “sooners.” Later other strips of territory were opened, and settlers poured in from the Midwest and the South.