Cooper is a city in and the county seat of Delta County, in the U.S. state of Texas. Located between the north and south forks of the Sulphur River, Cooper is the largest settlement in Delta County. At the 2020 United States census, the city had a population of 1,911. First inhabited by native people, Cooper was founded around 1870, at the same time that Delta County was established. Cooper grew rapidly and quickly became the center of local events.