Poplar is a city in Roosevelt County, Montana, United States. The population was 758 at the 2020 census. It is the tribal headquarters for the Fort Peck Indian Reservation, though Wolf Point is the most populous. The reservation is home to both the Assiniboine and Sioux Tribes, two distinct American Indian Nations.

Roosevelt County is a county in the U.S. state of Montana. As of the 2020 census, the population was 10,794. Its county seat is Wolf Point. Roosevelt County was created by the Montana Legislature in 1919 from a portion of Sheridan County. The name honors former president Theodore Roosevelt, who had died earlier that year.