Leesburg is an unincorporated community in southwestern Camp County, Texas, United States. It lies along State Highway 11 west of the city of Pittsburg, the county seat of Camp County. Its elevation is 397 feet (121 m). Although Leesburg is unincorporated, it has a post office, with the ZIP code of 75451; the ZCTA for ZIP Code 75451 had a population of 1,265 at the 2000 census. Named for early settler John Lee, Leesburg was a contender for county seat in 1874, coming in second to Pittsburg. In the same year, the community's first post office was established. Leesburg has declined from its height in the early 20th century; its population has fallen, and its schools have been consolidated into the Pittsburg Independent School District since 1955.