 The state ranks fourth in area, but 44th in population, and accordingly has the third-lowest population density in the United States.The economy is primarily based on services, with ranching, wheat farming, oil and coal mining in the east, and lumber, tourism, and hard rock mining in the west.Millions of tourists annually visit Glacier National Park, the Little Bighorn Battlefield National Monument, and three of the five entrances to Yellowstone National Park.