Castro County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 7,371. Its county seat is Dimmitt. The county was named for Henri Castro, who was consul general to France for the Republic of Texas and the founder of a colony in Texas.

Parmer County is a county located in the southwestern Texas Panhandle on the High Plains of the Llano Estacado in the U.S. state of Texas. As of the 2020 Census, the population was 9,869. The county seat is Farwell. The county was created in 1876 and later organized in 1907. It is named in honor of Martin Parmer, a signer of the Texas Declaration of Independence and early judge. Parmer County was one of 10 prohibition, or entirely dry, counties in the state of Texas, but is now a wet county.