Littleton, city, seat of Arapahoe County and also in Douglas County, central Colorado, on the South Platte River, near Denver; laid out early 19th century, incorporated 1890. Major manufactures include aerospace products, motor vehicles, photographic equipment, tires, and electronic items. Arapahoe Community College, which has a museum of anthropology, and the Littleton Historical Museum are here. Population 28,631 (1980); 33,685 (1990); 40,340 (2000).