• The Continental Divide of the Americas, or merely the Continental Divide or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from, 1) those river systems which drain into the Atlantic Ocean (including those which drain via the Gulf of Mexico or the Caribbean Sea), and 2) along the northernmost reaches of the Divide, those river systems which drain into the Arctic Ocean (including those which drain into either the Arctic or Atlantic Oceans via Hudson Bay).
http://en.wikipedia.org/wiki/Continental_Divide
  • In the conterminous United States, it follows the crest of the Rocky Mountains. The National Atlas of the United StatesĀ® compiled this map layer by extracting the appropriate lines from the Hydrologic Unit Boundaries layer of the National Atlas.
http://www.nationalatlas.gov/mld/condivl.html

ContinentalDivide3.gif
Map Of Continental Divide