Hill Country State Natural Area is in Bandera and Medina counties, 52 miles northwest of San Antonio. The state acquired the 5,369.8-acre site by gift and purchase in 1976. The natural area opened in 1984.

The Merrick Bar-O Ranch donated most of the site. The owners stipulated that it "be kept far removed and untouched by modern civilization, where everything is preserved intact, yet put to a useful purpose."