The Upper Marlboro Residential Historic District is a national historic district encompassing a historic residential area of Upper Marlboro, Maryland. The area reflects the town's growth from the 18th to the 20th century, including its importance as the county seat of Prince George's County. The district also contained a significant post-American Civil War African-American population, which was making the transition from slavery to freedom. Located in the district are three previously listed properties: Kingston, Content, and the John H. Traband House. Prominent features of the district include the Trinity Episcopal Church at 14519 Church Street, an 1846 Gothic Revival church designed by Robert Carey Long, Jr., and 5415 Old Crain Highway, a 1 1/2-story wood frame house dated to c. 1730, wh