The county was named for Confederate general Thomas J. (Stonewall) Jackson. Stonewall was one of fifty-four counties formed by the Fifteenth Texas Legislature in 1876 from the Young and Bexar districts. It remained attached to Young County for judicial and all other governmental purposes until March 31, 1887, when it was attached to Jones County for convenience. In 1888 the residents of the county petitioned the Jones County Commissioners Court to hold an election for the organization of the county. The balloting took place on December 20 of that year. However, the question of the county seat had been omitted from the ballot. On June 12, 1889, W. E. Rayner granted land for a townsite, and the new town of Rayner became the county seat. Beginning in 1892 the citizens of Aspermont made several attempts to make their rapidly growing town the county seat, and finally succeeded after an election held in June 1898. The controversy did not really end, however, until March 1900, when a contract to build a new courthouse in Aspermont was signed. Rayner soon ceased to exist.
-Handbook of Texas Online: Stonewall County