Colmar Manor is a town located in Prince George's County, Maryland, United States.

[4] As the town developed at the beginning of the 20th century, it assumed a name derived from its proximity to the District of Columbia—the first syllable of Columbia and that of Maryland were combined to form "Colmar".

The most famous duel fought on the site was on March 22, 1820, between Stephen Decatur and James Barron.

The place became a battlefield again in the early days of the Civil War when Confederate troops mounted an assault on Battery Jameson, Fort Lincoln, now northeast Washington, D.C., which was one of a number Union defensive forts built around the nation's capital to protect it from capture.

[5][7] In 1912, the Capitol Cemetery of Prince George's County was incorporated on the Washington, D.C., boundary line.

[6] The 260-acre (1.1 km2) farm site was used by the 6,000 jobless men from Ohio who descended on the Capitol in 1894 as "Coxey's Army".

[6] The streets were originally named after President Woodrow Wilson (1913–21), members of his cabinet, and other prominent men of the era.

[5] The location of the development within the first service area of the Washington Suburban Sanitary Commission offered homeowners modern water and sewer lines.

In 1959, a municipal building was constructed to house the town's administrative offices and police department.

[6] During the second half of the 20th century, the area along Bladensburg Road, now known as Alternate Route 1, became lined with commercial establishments, and much of the housing stock was used as rental units.

A large urban renewal project in the 1970s and 1980s resulted in the demolition of many commercial properties along Bladenburg Road.

The Colmar Manor Community Park was established along the west bank of the Anacostia River in the 1970s on the site of a sanitary landfill.

[6][9][10] In 1999, Colmar Manor, Bladensburg, and Cottage City were lauded by the Joint Center for Sustainable Communities for their collaboration with Prince George's County for the Port Towns Revitalization Initiative, which created a common Port Towns identity for the towns; encouraged businesses development through infrastructure and facade improvements; acquisition of historic properties and plans for their reuse; and reconstruction of the Bladensburg waterfront, marina and the Bladensburg Waterfront Park.