Dumas is a city and the county seat of Moore County, Texas, United States. The population was 14,501 at the 2020 census. Located approximately 40 miles north of Amarillo, the city is named for its founder, Louis Dumas. Dumas Avenue, the main thoroughfare, is also United States Highways 87 and 287. Window on the Plains Museum, which offers exhibits on Moore County and the Texas Panhandle, is located on South Dumas Avenue, the main thoroughfare.