Flat is at the intersection of State Highway 36 and Farm Road 931, ten miles southeast of Gatesville in southeastern Coryell County. The name Mesquite Flat was originally chosen because of the local terrain and vegetation, but when residents applied for a post office in the 1890s, the postal department rejected the name. They then submitted the name Flat, and in 1897 were granted a post office by that name. Flat had a cotton gin, three general stores, and 100 residents in 1914. Population estimates fell to twenty-five in the mid-1920s but rose again to 125 by the late 1930s. Farming was the primary occupation of area residents until the 1940s, when much of the farm acreage was taken over by the establishment of Fort Hood. In the 1950s and 1960s Flat became home to military and civilian personnel associated with Fort Hood as well as to people who commuted to work in Gatesville or Temple. The population of the community was estimated at 200 in 1960 and 210 in 1970. The school at Flat was consolidated with the Gatesville Independent School District in 1963, and in the early 1980s residents converted the old school building to a community center. Population estimates for Flat remained at 210 through 2000.