A conversation between two co-workers almost ended up in an argument when one of them (Eastern born and raised) made a comment about the “continental divide,” referring to the Eastern Continental Divide (Appalachian Mountains).
The other co-worker (Western born and raised) countered that the “continental divide” in the Rocky Mountains. After several minutes of disagreements, I injected myself into the discussion. My explanation was the the term “continental divide” (small letters) just meant a dividing line of stream directions. “Continental Divide” in caps (not something you can see in normal speech) refers specifically to the one in the Rockies.
The (western) co-worker was not sold on it, though, countering that “There’s only one continent. There should be only one continental divide.”
After trying to explain it several different ways, I could see that this was not something I was going to win—and it was close to quittin’ time anyway.
The question:
My 1980 Merriam-Webster dictionary tends to support my explanation of “continental divide.” Interestingly, there’s no entry of “Continental Divide” in the geographic supplement.
However, my 1992ish M-W no longer has a dictionary entry for “continental divide” at all. Instead, there’s a geographic entry for “Continental Divide,” also known as “Great Divide.” This is also reflected on m-w.com.
My understanding is that a “continental divide” is the dividing line of directions of two drainages that then flow into different oceans. That’s more than just “a dividing line of stream directions,” though maybe that’s what you meant? But the “continental” part is “goes to a whole 'nother ocean,” not just “goes in a different direction.” This understanding seems to be supported by the Wiki definition here. Wiki also supports the idea that there is an eastern continental divide in the U.S., as well as the western one which, as you note, is known as “The Great Divide.” Link. I didn’t know there was more than one, so consider ignorance fought!
The Great Divide in the Rockies is the most significant because it splits the watersheds the most, towards the pacific or towards the Atlantic (or connecting bodies of water.) It is also the one peopel generally think of as teh COntinental Divide. But, as mentioned by Musicat, any major watershed split can be called a divide. Near Hibbing, Minnesota there is a hill which, depending on the side, has water flowing towards the Atlantic by way of the Great Lakes and the St. Lawrence Seaway, or through Lake of the Woods, Lake Winnipeg and Hudson Bay, or along the Mississippi through the Gulf of Mexico.
The original Continental Divide was a line, in some places well demarcated and in others a bit more abstract, that divided areas drained by streams/rivers ultimately flowing into the Atlantic/Gulf from those that flowed into the Pacific (or a local basin with no exterior drainage, as for example Great Salt Lake and the end of the Humboldt River).
As drainage basin geography became more important, and transcontinental shipment dealing with natural features less, more divides were nominated. One of the first was the line through the Appalachians differentiating the Tennessee/Cumberland/Ohio drainage into the Mississippi and Gulf from the assortment of rivers (Susquehanna, Shenandoah/Potomac, Roanoke, etc.) that drain into the Atlantic. Another differentiated the Mississippi and its tributaries from the Great Lakes/St. Lawrence drainage basin.
The process can be continued almost indefinitely. Odds are that EddyTeddyFreddy and RTFirefly can identify small streamlets near their homes that flow into Massachusetts and Chesapeake Bays respectively which the rest of us have never heard of, but which constitute drainage basins on the same independent level of “collects water from a land area and drains into the ocean” as the Mississippi-Missouri-Ohio and Great Lakes-St. Lawrence, and Colorado drainage basins.
Not to mention that a whole lot of Canada is within the drainage basin for the Arctic Ocean, not the Atlantic Ocean/Gulf of Mexico. So a significant part of the “Continental Divide” doesn’t divide up the Pacific from the Atlantic at all.
The Continental Divide in central Panama actually did disappear in 1914 with the creation of the Panama Canal. Water from the Chagres River orginally flowed into the Atlantic Ocean (Caribbean Sea) but now also flows into the Pacific via the Gaillard Cut of the Canal. The Chagres now has a bi-oceanic drainage. (However, by convention the former Continental Divide is still recognized as the boundary between Panama’s Atlantic and Pacific slopes in the region.)
Here is a detailed map of North American watersheds. What I’ve always heard called THE Continental Divide is the boundary between the Pacific watersheds and the Atlantic watersheds running through the Rockies. Said divide nicely fits for the US, but to the north, they get divided by the Arctic Ocean drainage basin (and the north-south divide between entering the Atlantic via Hudson Bay, or via the Gulf of Mexico), and to the south there are large internal drainage areas between Atlantic and Pacific drainage.
Also nice on the map seeing where borders follow drainage basin borders and where they follow the rivers themselves.
And here is some information about a couple “holes” in the Divide in Wyoming. One is an internal drainage area where the water reaches neither ocean, and the other is a stream that splits both ways across the divide.
Things are much easier for me. I’m pretty sure everything here makes its way four blocks to the Charles River, and then less than two miles to Boston Harbor in the Atlantic Ocean.
In western Maryland there’s a sign on I-68 marking the eastern continental divide. Streams east of it at that point flow into the Atlantic via the Potomac and the Chesapeake Bay, and those west of it flow into the Gulf of Mexico via the Ohio and Mississippi. There also one in Ohio marking the division between streams which flow into Lake Erie and those which flow into the Ohio River.
In British English we call it a “watershed”, not a divide. There’s quite a, um, divide in meaning of the word on either side of the Atlantic. In America, the watershed is the whole area drained by a river system, and watersheds are separated by divides. In Britain, the drainage area is more commonly known as a “drainage basin”, and these are divided by watersheds. Clear?
A guy walked the watershed of Scotland a few years back. Unfortunately for my linguist point above, he subtitled his account of the walk “The Border to Cape Wrath Along Scotland’s Great Divide”…
Where have you seen such a sign in Ohio? Mostly, that border is quite snaky, and there is very little of Ohio included in the lake drainage system, other than in the NW where the Maumee and its tributaries flow.
The preferred definition for watershed is as a divide, and in that way is used in a larger sense to talk about decisions that can be considered turning points or crucial boundaries.
I pass the one in Maryland frequently, so my memory of it is clearer, and it says “Eastern Continental Divide”. The sign I saw in Ohio was up toward your area, when I was returning from Michigan. I don’t think it used the word “divide”, it probably said something about leaving the great lakes drainage. The area of Ohio that drains into Lake Erie may be bigger than you think; it looks to me on this site to be close to a quarter of the state. But it is, as you say, much bigger in the northwest part of the state.
As has been noted, many states have “divides.” Iowa’s divide marks a line such that streams east of it go to the Mississippi and those west to the Missouri. It’s location is marked by such towns as Superior, Alta, and Creston.
As far as I am concerned, and that’s all that counts with me, there is just one continental divide in the US. That one is in the Rocky Mountain range starting in the International Peace Park in Montana and running down to near Douglas, AZ.
It’s similarly difficult in Europe. The European divide is the line running across the continent approximately southwest to northeast, with the Alps forming an important part of it. Water raining down on the north or west of the linie ultimately drains into the Atlantic, the North Sea or the Baltic Sea, water on the south or east into the Black Sea or the Mediterranean. But all of the seas mentioned are marginal seas of the Atlantic, the only ocean Europe has access to.
Likewise, here in Illinois there is a suburb of Chicago called Summit, which name must be puzzling to outsiders as the land is flat as a pancake. Summit rears a few inches above the surrounding terrain, however, which is enough to separate Great Lakes drainage from Mississippi River drainage. The easy breaching of this ultra-low divide, and the proximity of navigable water in each direction, is of course the reason for the existence of the Chicago metropolitan area.
The Great Lakes/Mississippi divide is the third most important, geographically and historically, in North America. The most important, of course, is the Continental or Great Divide—most important because the oceans it separates, the Atlantic/Arctic and the Pacific, are as separate as oceans can be (linked only at the remote Bering Straits and Cape Horn) and because it’s marked by the crown of the continent, the Rocky Mountains.
The second most important divide is the North/South divide separating Hudson Bay/Arctic drainage from Gulf of Mexico/Atlantic drainage. West of the Great Lakes, this divide forms the basis for the US/Canada boundary, although we smoothed it out at the 49th parallel. South of the divide, rivers are navigable year-round, which explains why the United States was settling the Midwest and West while western Canada was still locked up by the Hudson’s Bay Company.
The third most important divide is the aforementioned one between the Great Lakes/St. Lawrence and the Gulf of Mexico/Lower Atlantic. Unlike the previous divide, this one straddles the US/Canada boundary rather than demarcating it. The breaching of this divide via the Erie and I&M canals, enabling the American Midwest to trade directly with Europe, was a signal moment in American history.
The fourth most important divide is the Appalachians, separating the Mississippi/Ohio basin from land draining directly eastward. Daniel Boone discovered of the land route (Cumberland Gap) over this divide, and George Washington vainly hoped to breach it via the Chesapeake & Potomac Canal.
