The Continental Divide separates the Atlantic and Pacific watersheds of North America. In Glacier, the divide follows the crest of the Lewis Range from Marias Pass to Flattop Mountain and then swings west to the crest of the Livingston Range, which it follows into Canada. The Continental Divide forms the western border of Waterton Lakes National Park, which lies completely on the east side of the divide. In Waterton, all drainages flow into the Saskatchewan River Basin, generally a northeast route towards Hudson Bay.
In Glacier National Park, there is actually a triple divide because waters potentially can flow into three drainages. The creeks and streams in the southeast section of the park feed into the Birch and Marias Rivers, then the Missouri and the Mississippi and empty into the Gulf of Mexico. The water in the northeast section feeds into the
Glacier's Triple Divide Peak (8020 ft/2446 m) is a rather rare hydrologic feature. From the summit, water flows to the Atlantic Ocean, the Pacific Ocean, and Hudson Bay. The peak can be viewed from the Going-to-the-Sun Road in the Two Dog Flats area, on the east side of the park. Other triple divides (hydrological apexes) are found in Jasper National Park and in Siberia.