According to the United States Census Bureau, the city has a total area of 7.0 square miles (18.0Square kilometers). 7.0 square miles (18.0Square kilometers) of it is land and none of the area is covered with water. The highest point of elevation in the county is at the location that the courthouse in Decatur currently occupies. The intent of placing the town on this high point of elevation was to be able to sight and ward off any incoming attacks or raids by Native Americans. Decatur is a city located in Wise County, Texas, United States. This city was named after Stephen Decatur, Jr. The population was 5,201 at the 2000 census. A July 1, 2008 U.S. Census Bureau estimate placed the population at 6,432. It is the county seat of Wise County. Decatur is part of the Dallas/Fort Worth Metroplex and is located 25 miles northwest of Fort Worth and 45 miles northwest of Dallas.