Flat, arid, grassy land in Reeves County had a moderate water supply from the Pecos River and springs in Toyah Valley. Yuma Indians are thought to have practiced irrigated farming here in the 16th century. Mexicans later raised vegetables and grain. Cattlemen moved in during the 1870s. The Texas & Pacific Railway opened the route to El Paso in 1882, and farmers, merchants, and mechanics settled in Pecos City and Toyah. The county was organized in 1884. Modern irrigated agriculture began about 1900. The only dam on the Pecos River in Texas was built in this county in 1935, and privately owned deep wells are also used.