Geography

Updated: February 2, 2026

The Continental Divide is like a giant "roof line" running along the high crests of the Rocky Mountains from Canada all the way to Mexico. When rain or snow falls on one side of this line, the water eventually flows to the Pacific Ocean; when it falls on the other side, it eventually flows to the Atlantic Ocean or the Gulf of Mexico. In Montana, the Divide cuts through the western part of the state, including Glacier National Park and other tall mountain ranges.

Montana is called a "headwaters state" because many big rivers start, or have important beginnings, in its mountains. Snow that falls in winter slowly melts in spring and summer, feeding creeks and rivers that carry water hundreds or even thousands of miles away. These rivers help supply drinking water, irrigation for farms, and power from dams for many communities both inside and outside Montana.

Within Montana's borders are parts of two major river systems of North America. On the west side of the Continental Divide, rivers like the Kootenai, Clark Fork, Blackfoot, Bitterroot, and Flathead flow into the Columbia River system, which eventually reaches the Pacific Ocean. On the east side of the Divide, water flows into the Missouri River system. At a place called Three Forks, three rivers-the Jefferson, Madison, and Gallatin-join together to form the Missouri River, which later meets the Mississippi River and finally reaches the Gulf of Mexico.

Because of this, the water that starts as snowflakes in Montana's mountains doesn't just stay in the state. It becomes part of huge river networks that connect Montana to distant places like the Pacific Northwest, the central United States, and even the ocean coasts far away.

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Updated: February 2, 2026