The western third of the state contains numerous mountain ranges; other 'island' ranges are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographic and geographical fact is reflected in the state's name, derived from the Spanish word montaña 'mountain', from Latin. The state nickname is the "Treasure State." Other nicknames include "Land of Shining Mountains," "Big Sky Country," and the slogan "The Last Best Place." The state ranks fourth in area, but 44th in population, and therefore has the third lowest population density in the United States.

The economy is primarily based on ranching and wheat farming in the east, lumber and tourism in the west, oil and coal in the east, and hard rock mining in the west. Millions of tourists annually visit Glacier National Park, the Battle of Little Bighorn site, and three of the five entrances to Yellowstone National Park.