Wyoming's neighbor is Montana, which is a state in the United States located in the western region of the country. It borders Wyoming to the south, Idaho to the west, North Dakota and South Dakota to the east, and the Canadian provinces of Alberta, Saskatchewan, and British Columbia to the north. Montana is the fourth largest state in the US by area, and the eighth least populous state. It is known for its diverse terrain, which includes the Rocky Mountains, the Great Plains, and part of the northern Great Basin.