Billings is located in southern Montana on the Yellowstone River. Billings is the largest city in Montana and the commercial, shipping, and processing center of a region that produces cattle, wheat, and sugar beets. The city is the site of oil refineries, two large hospitals and related medical services, shopping centers. The city functions as a gateway to Yellowstone National Park, the Crow Indian Reservation, Little Bighorn Battlefield National Monument, and nearby ski and recreation areas. A 2005 real estate survey has estimated the population of Billings, Montana at 98,721.