ridge of the Rocky Mountains forming a North American watershed that separates rivers flowing in an easterly direction from those flowing in a westerly direction
See Continental Divide in American Heritage Dictionary 4
noun
An extensive stretch of high ground from each side of which the river systems of a continent flow in opposite directions.
A series of mountain ridges extending from Alaska to Mexico that forms the watershed of North America. Most of it runs along peaks of the Rocky Mountains and is often called the Great Divide in the United States.