There are 6 US Post Offices in Delta County serving a total of 4,966 residents equating to 828 residents per post office. It's estimated that approximately 7,926 packages are handled across the 6 county post offices annually. Delta County is a county located in the U.S. state of Texas. As of the 2010 census, its population was 5,231. Its county seat and largest city is Cooper. The county was founded in 1870 and is named for its triangular shape, much like the Greek letter delta. Two forks of the Sulphur River form its northern and southern boundaries, and meet at its easternmost point. Delta County is one of 19 prohibition, or entirely dry, counties in the state of Texas. As of 2015, Delta county is no longer a dry county. Delta County is represented in the Texas House of Representatives by Republican Larry Phillips of Sherman, Texas."