Perhaps you remember hearing about the Continental Divide in the Rocky Mountains, separating waters that flow to the Pacific Ocean vs. the Gulf of Mexico. Lewis and Clark crossed that divide at Lemhi Pass on the current Montana/Idaho border, near Missoula. Many emigrants travelling to the west coast, including the '49's rushing to California after the discovery of gold, crossed at South Pass in modern-day Wyoming.
The first Americans to cross the western continental divide were recent immigrants from Russia who had crossed the Bering land bridge. They were headed east, though presumably in small hunting and gathering trips rather than on an intentional cross-continental journey. Perhaps 15,000 years later, long after it had become routine for the local Native Americans to go back and forth over the Rockies, Lewis and Clark arrived.
They were the first Virginians to cross the Continental Divide, headed west initially and then eastward on the way home. Those explorers were looking, in part, for the closest thing to a water-level passage to the Pacific in 1804-1806. Under the guidance of that other Virginian, President Thomas Jefferson, they followed the Missouri River upstream seeking a water gap. They did not know that the topography of the Rockies would offer a far-better alternative at South Pass, far to the south of where they first crossed the Rockies near Missoula, Montana.
The Eastern Continental Divide separates the waters flowing to the Atlantic from those flowing to the Gulf of Mexico. The airport at Blacksburg is on the Eastern Continental Divide. Some rain runs off it to the north, into Cedar Run and the North Fork of the Roanoke River and down to Albermarle-Pamlico Sound in North Carolina. But rain running to the south will drain into Stroubles Creek and then the New River. That water will flow through West Virginia, down the Ohio River, and with the Mississippi past New Orleans. After dropping a little bit of sediment from Montgomery County into the birds-foot delta of the Mississippi River, the water from the Blacksburg Airport will finally enter the Gulf of Mexico.
In addition to the airport at Blacksburg, you can see it on Route 460 west of Virginia Tech. Drive west from the campus towards West Virginia, climb to the crest of Brush Mountain, and when you come down off the mountain you will see an intersection with two dirt roads. (The old topographic map - see image to the right - shows the old road alignment, where a traveller headed west would see the dirt road to the right long before the left-hand turn.)
At the intersection, on the left look for the US Forest Service sign for Pandapas Pond. That artificial pond marks the headwaters of Poverty Creek. It flows into Toms Creek and joins the New River at Whitethorne, roughly 500 feet lower in elevation.
Forest Service Road 621 is on your right, and runs parallel to Craig Creek north to Route 311. (Route 311 connects New Castle, the county seat of Craig County, with Roanoke.) Craig Creek flows north across Route 311 and ultimately into the James River, just upstream of Eagle Rock and halfway between Clifton Forge and Buchanan. The rain that falls on the north side of US 460, across the highway from Pandapas Pond, drops roughly 1100 feet before reaching the James River.
Craig Creek and Poverty Creek are both eroding away at the ridge which separates them, the ridge on which US 460 runs. At some point in the future, after Craig Creek carves its valley 500 or 1000 feet deeper, it is likely to intercept the New River. The upper New River will one day be diverted to flow into the James and on to the Atlantic Ocean rather than to the Gulf of Mexico. It's called "stream piracy" when a stream is diverted into another watershed.
Don't assume the Eastern Continental Divide, or any divide, must be a crest as sharp as a knife's edge. Many of those driving on US 460 never realize they are crossing the Eastern Continental Divide just west of Blacksburg.
Out west, the Continental Divide can be equally obscure. South Pass in Wyoming is the famous crossing point for settlers traveling west in the 1800's. Cross it on Interstate 80, and you'll hardly notice the shift from going uphill to downhill. Of course, that's why emigrants with only 4 horses instead of a Sport Utility Vehicle thought it was such a great choice for traveling west.
The divide between the New River and the headwaters of the Tennessee River is at Rural Retreat (where the soft drink Dr. Pepper was invented) in Wythe County. Even a bicyclist on Route 11 would have to be paying attention to notice that divide.
| James River/Shenandoah River Divide Follow Route 11 (or Interstate 81) north to the divide between the Shenandoah and James Rivers at Steele's Tavern. It too is a subtle rise rather than a clear dividing line. In this case, the headwaters are etching away at the same bedrock, and the relative energy of the two streams is basically the same at this site. There's no clear ridgeline visible to identify the watershed boundaries; you have to notice which way the creeks are running to identify the divide in any particular spot. Coincidentally, Steele's Tavern is also the home of invention. The McCormick reaper was developed here, on the boundary of Augusta and Rockbridge counties and on the divide between the James and Shenandoah/Potomac watersheds. |  Map source: Virginia Highway Map, 1998- 99 |
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