The incorporated Town of Upper Marlboro is 0.8 square miles, one mile across and half a mile wide. Once a port town, the Town is on the Western Branch of the Patuxent River. The main stem of the Patuxent River, not far from the Town, forms the eastern border of Prince George’s County.
The Town is among the oldest of the surviving southern Maryland towns with a history dating back to colonial times. The area was settled around 1695 and named after the first Duke of Marlborough — an ancestor of Winston Churchill. It was established as a port town for tobacco shipments in 1706, when the western branch of the Patuxent River was still navigable for tobacco vessels. It has been the county seat of Prince George’s County since 1721.
The town is the birthplace of John Carroll, the first Catholic Archbishop in America and founder of Georgetown University, and of his brother Daniel, a signer of the U.S. Constitution. Throughout its history, Upper Marlboro has been the home or place of work of prominent national, state, and local figures. In recent times, it was the home of the late Lansdale G. Sasscer, Sr., Maryland State Senator, 1922-1938, and U.S. Congressman, 1939-1953.
The Town of Upper Marlboro has a downtown area along Main Street, which is home to a variety of local business as well as the Prince George’s County Courthouse and the County Administration Building. The main Board of Education offices for the Prince George’s County Public School system are a short walk from Main Street. Additional businesses and government offices are located in the Old Mill complex a short distance from downtown.
The main residential area is the to the west of the downtown on several quiet streets. The Town has about 313 dwelling units, mostly single-family homes with 657 official residents in according to the 2008 cencus. Numerous civic organizations in and near the town contribute to the sense of community and “small town” atmosphere that characterizes life in The Town of Upper Marlboro.
When people make reference to Upper Marlboro or Marlboro, may not be referring to the “Town”. There are two ZIP codes that the United States Post Office has labeled “Upper Marlboro” (20772 and 20774), as well as three post office boxes (20773, 20775 and 20792). These Zip codes constitute Greater Upper Marlboro, a geographical area that is about one-fifth of the total area of Prince George’s County!