After the Civil War, the two nations were forced to cede the land to the US government under terms of new treaties required because they had been allies of the Confederacy.

In 1869, the former Leased District was designated by the President as the Cheyenne and Arapaho Indian Reservation, following their removal from further west.

Under the Dawes Act of 1891, the government split up such communal lands, allocating plots to individual households of various tribes.

In 1892, the government opened such surplus land to settlement by non-Indians, attracting numerous European-American settlers and immigrants.

The Gannett survey of 1927-1929 found that the true 100th Meridian, the boundary between Texas and western Oklahoma, was 3,800 feet (1,200 m) farther east than previously thought.

The US Supreme Court ruled on March 17, 1930 that the strip of land must be returned to Texas, thereby reducing Beckham County's area slightly.

[4] The county is drained by the North Fork of the Red River and its tributaries: the Timber, Sweetwater, and Buffalo creeks.

The major crops have been cotton, wheat, alfalfa, kafir, milo maize, and broomcorn.

[3] School districts include:[13] The following sites in Beckham County are listed on the National Register of Historic Places: