What is the Continental Divide?

It's All About How the World's Rivers Flow

Ocean Drainage of the World - Continental Divides
There are many continental divides in the world, the best-known is the one that divides North America from east to west. Citynoise/Wikimedia Commons

Every continent except for Antarctica has a continental divide. Continental divides separate one drainage basin from another. They are used to define the direction that an area's rivers flow and drain into the oceans and seas.

The best-known continental divide is in North America and it runs along the Rocky and Andes mountain ranges. Most continents have multiple continental divides and some rivers flow into endorheic basins (inland bodies of water), such as the Sahara Desert in Africa.

The Continental Divide of the Americas

The Continental Divide in the Americas is the line that divides the flow of water between the Pacific Ocean and the Atlantic Ocean.

  • Rain or snow that drains on the east side of the Continental Divide flows toward the Atlantic Ocean.
  • Precipitation on the west side drains and flows toward the Pacific Ocean. 

The continental divide runs from northwestern Canada along the crest of the Rocky Mountains to New Mexico. Then, it follows the crest of Mexico's Sierra Madre Occidental and along the Andes Mountains through South America.

More Water Flow Divides in the Americas

To say that any continent, including North America, has a single continental divide is not entirely true. We can continue to divide the flow of water (called hydrological divides) into these groups:

  • East of the Rocky Mountains and north of the Canada-U.S. border, the rivers flow into the Arctic Ocean.
  • Most rivers of the central U.S. flow into the Gulf of Mexico via the Mississippi River. Indirectly, this is an Atlantic Ocean drainage.
  • Rivers on the east side of Mexico and Central America also drain into the Gulf of Mexico.
  • Rivers around the Great Lakes and along the entire east coast of Canada and the U.S. flow directly into the Atlantic Ocean.
  • South America has a true east-west continental divide. Everything east of the Andes flows into the Atlantic Ocean and everything west flows into the Pacific.

The Continental Divides of the Rest of the World

It is easiest to talk about the continental divides of Europe, Asia, Africa, and Australia as a whole because many of the drainage basins span all four continents.

  • The Atlantic Ocean: Along the entire western coast of Europe and Africa, the rivers flow into the Atlantic Ocean.
  • The Mediterranean Sea: The southern part of Europe, most of the country of Turkey, and many rivers in the northern part of Africa drain into the Mediterranean Sea. Most notably, the Nile River flows north and has a drainage basin that reaches south past the equator.
  • The Indian Ocean:  The rivers of countries that surround the Indian Ocean flow into it. This includes most of the eastern coast of Africa, the Middle East, India, and Southeast Asia as well as the majority of Australia.
  • The Pacific Ocean: Along the eastern coast of Asia and Australia, the rivers flow into the Pacific Ocean. This includes China and much of Southeast Asia along with all of the island nations that fill this area of the Pacific.
  • The Arctic Ocean: The majority of Russian rivers flow into the Arctic Ocean.
  • Endorheic Basins: Asia and Africa are home to the largest endorheic basins where the rivers empty into deserts, large lakes, or inland seas.