Rockwall is a city in Rockwall County, Texas, United States. It is part of the Dallas/Fort Worth Metroplex. The population was 17,976 at the 2000 census. It is the county seat of Rockwall County. Rockwall County is the second wealthiest county in the state of Texas in terms of median income. The majority of its residents enjoy a relatively high standard of living. The name Rockwall is derived from a naturally jointed geological formation, which has the appearance of an artificial wall.