Carlsbad is a census-designated place and unincorporated community in northwestern Tom Green County, Texas, United States. It lies along U.S. Route 87, northwest of the city of San Angelo, the county seat of Tom Green County. Its elevation is 2,024 feet. Although Carlsbad is unincorporated, it has a post office, with the ZIP code of 76934; the Z…Carlsbad is a census-designated place and unincorporated community in northwestern Tom Green County, Texas, United States. It lies along U.S. Route 87, northwest of the city of San Angelo, the county seat of Tom Green County. Its elevation is 2,024 feet. Although Carlsbad is unincorporated, it has a post office, with the ZIP code of 76934; the ZCTA for ZIP Code 76934 had a population of 1,332 at the 2000 census.