Mount Rainier /re??n??r/ is a city in Prince George's County, Maryland, United States. The population was 8,080 at the 2010 census. Bordering Washington, D.C., Mount Rainier got its start as a streetcar suburb. 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.