The 'Chicago Portage' connects the
watersheds ''(
BrE: drainage basin)'' and the
navigable waterways of the
Mississippi River and the
Great Lakes. It crosses the
continental divide that separates the Great Lakes and
Atlantic Ocean watersheds from the
Gulf of Mexico watershed.
The
St. Lawrence Seaway Divide runs less than a mile from the shores of
Lake Michigan, and is at places only 17 feet higher than the water level in the lake. A breach of the ridge could potentially cause the Great Lakes to flow southwards to the Gulf of Mexico.
The
portage was discovered in
1673 by Europeans when the
French Canadian explorers,
Louis Joliet and
Father Jacques Marquette, were
canoeing upstream on the Mississippi River. They received some navigational tips from native
Indians and continued along the
Illinois and
Des Plaines Rivers.
There, according to Joliet, a canal of ''"half a
league'' (about 2 miles, 3 km) across the Chicago Portage would allow easy navigation from
Lake Erie to the Gulf of Mexico.
The city of
Chicago grew up on the portage.
In
1848 Illinois and Michigan Canal was opened, breaching the
water divide and enabling navigation between the two waterways. In
1900 it was replaced by the larger
Chicago Sanitary and Ship Canal. After the
Chicago River was diverted to the new canal, the Mississippi watershed is now separated from the Great Lakes by only a few downtown Chicago
locks. The quantity of water allowed to pass (and thus diverted from the
St. Lawrence River) is regulated under international treaty between the U.S. and
Canada.
External links
★
Jolliet and La Salle's Canal Plans at
Encyclopedia of Chicago
★
The Continental Divide in Oak Park