Dimmit County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 8,615. The county seat is Carrizo Springs. The county was founded in 1858 and later organized in 1880. It is named after Philip Dimmitt, a major figure in the Texas Revolution. The spelling of the county name and the individual's name differ because of a spelling error in the bill creating the county name.