Mount Rainier is a city in Prince George's County, Maryland, United States, bordering Washington. The population was 8,080 at the 2010 census. Mount Rainier is contained between the Northwest Branch Anacostia River, Cedar Lane Alley, and 34th Street to the north, 37th Street and 37th Place to the northeast, Upshur Street and Queens Chapel Road to the west, the Cargo Train tracks to the east, and Eastern Avenue NE to the south. Mount Rainier got its start as a streetcar suburb, when tracks were laid for the 82 Streetcar Line. According to local tradition, surveyors from the Pacific Northwest named the town, giving the streets names such as Shasta and Cascade. Historic U.S. 1 runs through the center of the town and serves as the main street and central business district.
Mount Rainier is located at 38°56′30″N 76°57′49″W (38.941594, -76.963696).
According to the United States Census Bureau, the city has a total area of 0.65 square miles (1.68 km2), all land.
Mount Rainier has attracted a significant gay and lesbian population. In 2000, same-sex couples accounted for 1.0 percent of households, almost double the national average.
As of the census of 2010, there were 8,080 people, 3,344 households, and 1,735 families residing in the city. The population density was 12,430.8 inhabitants per square mile (4,799.6/km2). There were 3,601 housing units at an average density of 5,540.0 per square mile (2,139.0/km2).