Montana is a state in the United States. Its capital is Helena, and the largest city is Billings. Montana has many mountains in the western half of the state. Most of the eastern part of the state is prairie.
Montana and Canada share a 545-mile (877-km) part of the world's longest undefended (which means there are no soldiers or armies on either side) border. The state borders the Canadian provinces of British Columbia, Alberta, and Saskatchewan, more provinces than any other U.S. state.
To the east of Montana is North Dakota; to the southeast is a short border with South Dakota. In the south is Wyoming, and on the west and southwest is Idaho.