It is the fourth-largest state by area , but the eighth-least populous state and the third-least densely populated state. Its capital is Helena , while the most populous city is Billings. The western half of the state contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands , with smaller mountain ranges found throughout the state.
Most of Montana first came under American sovereignty with the Louisiana Purchase from France in and was explored by the Lewis and Clark Expedition shortly thereafter. The ensuing gold rush, along with the passage of the Homestead Acts in , brought large numbers of American settlers to Montana.
Mining, particularly around Butte and Helena , would remain the state's main economic engine through the midth century.
Other significant economic resources include oil , gas , coal , mining , and lumber. The health care, service, defense, and government sectors are also significant to the state's economy. Montana's fastest-growing sector is tourism, with Harding Oregon , who complained that Montana had "no meaning".
For thousands of years, various indigenous peoples have inhabited the land that is now Montana. A part of southeastern Montana was used as a corridor between the Crows and the related Hidatsas in North Dakota. As part of the Missouri River watershed, all of the land in Montana east of the Continental Divide was part of the Louisiana Purchase in , except for a tiny portion in the northeast that is part of the Hudson Bay drainage. Subsequent to and particularly in the decades following the Lewis and Clark Expedition , European, Canadian and American traders operated a fur trade , trading with indigenous peoples in both western and eastern portions of the area.
