Final answer:
The Continental Divide is the line that marks the separation between rivers flowing eastward and westward in the Rocky Mountains, directing the watershed drainage towards the Pacific or Atlantic.
Step-by-step explanation:
The line of the highest points in the Rockies that marks the separation between rivers flowing eastward and westward is known as the Continental Divide. This geographical feature runs along the spine of the Rocky Mountains and extends from the northern reaches of North America, down through the United States, and into Mexico. It separates the watersheds that drain into the Pacific Ocean from those that drain into the Atlantic Ocean, indicating the flow direction of rivers depending on which side of the divide they originate.