In time, the Indian Territory was reduced to what is now Oklahoma. The Organic Act of 1890 reduced Indian Territory to the lands occupied by the Five Civilized Tribes and the Tribes of the Quapaw Indian Agency (at the borders of Kansas and Missouri). The remaining western portion of the former Indian Territory became the Oklahoma Territory.

Gray's new map of Texas and Indian Territory (c. 1876)

The Oklahoma organic act applied the laws of Nebraska to the incorporated territory of Oklahoma Territory, and the laws of Arkansas to the still unincorporated Indian Territory (for years the federal U.S. District Court on the eastern borderline in Ft. Smith, Arkansas had criminal and civil jurisdiction over the Territory).