Rockwall is a city in Rockwall County, Texas, United States, and a suburb of Dallas and part of the Dallas/Fort Worth Metroplex. It is the county seat of Rockwall County, which is the third wealthiest county in the state of Texas. The population was 37,490 at the 2010 census. The name Rockwall is derived from a naturally jointed geological formation, which has the appearance of an artificial wall.