Eastern Continental Divide

For the hiking trail along the divide, see Eastern Continental Trail.

A map of the principal hydrological divides of North America. The Eastern Continental Divide (orange line) demarcates two watersheds of the Atlantic Ocean: the Gulf of Mexico watershed and the Atlantic Seaboard watershed.

The Eastern Continental Divide, Eastern Divide or Appalachian Divide is a hydrological divide in eastern North America that separates the easterly Atlantic Seaboard watershed from the westerly Gulf of Mexico watershed. The divide nearly spans the United States from south of Lake Ontario through the Florida peninsula, and consists of raised terrain including the Appalachian Mountains to the north, the southern Piedmont Plateau and lowland ridges in the Atlantic Coastal Plain to the south. Water including rainfall and snowfall, lakes, streams and rivers on the eastern/southern side of the divide drains to the Atlantic Ocean; water on the western/northern side of the divide drains to the Gulf of Mexico. The ECD is one of six continental hydrological divides of North America which define several drainage basins, each of which drains to a particular body of water.

Course

File:2016-06-06 12 05 23 View west along U.S. Route 33 and West Virginia State Route 55 (Allegheny Drive) crossing the Eastern Continental Divide on top of Allegheny Mountain in Pendleton County, West Virginia.jpg

U.S. Route 33/West Virginia Route 55 crosses the Divide in Pendleton County, West Virginia

At its northern terminus, the Eastern Continental Divide originates at the Eastern Triple Divide, its intersection with the St. Lawrence Divide on a summit named Triple Divide Peak in Potter County, Pennsylvania, about 10 mi (16 km) south of the New York-Pennsylvania border. This point divides the eastern United States into three watersheds, those of the St. Lawrence River to the north, the Atlantic seaboard to the east, and the Gulf of Mexico to the west.

From north to south, the divide passes through the broader Allegheny Plateau region, following the boundary between the Allegheny River and Susquehanna River watersheds through most of Pennsylvania. At Blue Knob near Altoona, the Divide begins to follow Allegheny Mountain and then Little Savage Mountain. A few miles before the state border, the Divide begins to separate the Youghiogheny River and Potomac River watersheds.

In Maryland, the Divide runs significantly west of the Allegheny Front, following Backbone Mountain, and passing near the source of the North Branch Potomac River at the Fairfax Stone. The Divide then passes through a plateau of the Allegheny Mountains of West Virginia, passing between the north end of the Canaan Valley in the Cheat River watershed, and the Mount Storm Lake basin in the Potomac River watershed. The Divide then rejoins the Allegheny Front.

A significant portion of the Divide forms part of the border between West Virginia and Virginia along Allegheny Mountain and then Peters Mountain, separating the Greenbrier River and James River watersheds. It then makes a dramatic arc to the east around the Sinking Creek valley, and then follows the hill crest east of Blacksburg, Virginia, until it meets the Blue Ridge Mountains, which take the form of an escarpment separating the headwaters of the New River from that of the Roanoke River.

Just before the Divide passes into North Carolina, it begins to separate the New River and Yadkin River watersheds. It then separates upper tributaries of the Tennessee River from those of the Santee River. Its high point is on Grandfather Mountain at 6,366 ft (1,940 m); although Mount Mitchell is the highest point in the Appalachian Mountains, it is not on the Divide, but 4 miles west of it.

File:ECD Duluth GA.jpg

A monument marking the Eastern Continental Divide that shows where the watershed drains, located on the Duluth Town Green in Duluth, Georgia

In Georgia, the Divide generally separates the Apalachicola River watershed in the west from the Savannah River and Altamaha River watersheds to the east, passing through the Atlanta metropolitan area and extending past the southern end of the Appalachian Mountains southeasterly across the Georgia plateau. This marks the first time the western watershed drains directly to the Gulf of Mexico without reaching the Ohio River first. In southern Georgia, it separates the Suwannee River and Satilla River watersheds.

In Florida, the Divide generally follows the western edge of the St. Johns River, meandering into the low country of Northern Florida until it reaches central Florida. The southern terminus of the Eastern Continental Divide is at the northern edge of the Kissimmee River watershed, part of the Lake Okeechobee drainage basin.. The elevation here is about 70 ft (21 m).

South of here, the terrain consists of low swampland covered by a network of diverging canals and natural waterways. As such, the land is not clearly divisible between the Gulf of Mexico watershed and the Atlantic watershed.

The exact route of the ECD shifts over time due to erosion, tectonic activity, construction projects, and other factors.

Weather

Because the divide is at or in proximity to the highest terrain, air is forced upwards regardless of wind direction. This process of orographic enhancement leads to higher precipitation than surrounding areas. In winter, the divide is often much snowier than surrounding areas, due to orographic enhancement and cooler temperatures with elevation.

History

Prior to about 1760, north of Spanish Florida, the Appalachian Divide represented the boundary between British and French colonial possessions in North America. The Royal Proclamation of 1763 separated settled lands of the Thirteen Colonies from lands north and west of it designated the Indian Reserve; the proclamation border ran along the Appalachian Divide but extended beyond its Pennsylvania-New York terminus north into New England.

Red Creek west of the crest of the Allegheny Front in the Dolly Sods area of West Virginia; the creek originates along the Eastern Continental Divide, with its waters flowing to the Gulf of Mexico as part of the Ohio River watershed.

Seneca Creek, incised into the Allegheny Front west of Seneca Rocks, West Virginia. This short but steep creek originates along the Eastern Continental Divide; its waters flow into the Atlantic Ocean via the Potomac River and Chesapeake Bay.

Locations

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ECD points

Area	Point	Summit or other feature
Pennsylvania: Eastern Triple Divide	2,523 feet (769 m)	Triple Divide Peak, Ulysses Township, Potter County
Pennsylvania: Interstate 80
Pennsylvania: Babcock Ridge
Pennsylvania: Allegheny Mountain	2,167 feet (661 m)	summit near Allegheny/Gallitzin Tunnels
Pennsylvania: Allegheny Mountain	2,690 feet (820 m)	summit above Allegheny Mountain Tunnel (Pennsylvania Turnpike)
Pennsylvania: Allegheny Mountain	2,460 feet (750 m)	summit above Sand Patch Tunnel
Pennsylvania: Savage Mountain	2,392 feet (729 m)	railroad cut on Great Allegheny Passage
Pennsylvania/Maryland: Savage Mountain	2,840 feet (870 m)	highest summit of the Mason–Dixon Line
Maryland: Interstate 68	2,620 feet (800 m)	crossing near Green Lantern Road
Maryland: Savage Mountain	2,600 feet (790 m)	saddle point at planned route of 1828 C&O Canal
Maryland/West Virginia: Backbone Mountain	3,380 feet (1,030 m) (highest point)	Headwaters of Potomac River (Maryland's southern border) and Youghiogheny River
West Virginia: US Route 33 / State Route 55	3,295 feet (1,004 m)	Saddle Point at Pendleton County and Randolph County.
West Virginia: Interstate 64	2,460 feet (750 m)	Midland Trail: planned crossing for the 19th century James River and Kanawha Turnpike
Virginia: Jefferson National Forest	3,620 feet (1,100 m)	saddle point at Johns Creek headwaters (James River tributary), and near triple point of Mississippi River (W) & Chesapeake Bay (NE)/Albemarle Sound (Roanoke River) (SE)
Virginia: Appalachian Trail	3,397 feet (1,035 m)	Parallel Route Begin
Virginia: Blacksburg, Virginia	2,080 feet (630 m)
Virginia: Appalachian Trail	3,224 feet (983 m)	Parallel Route Begin
Virginia: Interstate 81	2,180 feet (660 m)	crossing
Virginia: Christiansburg, Virginia	2,180 feet (660 m)	2940 Riner Rd, Christiansburg, VA 24073
Virginia: Interstate 77	2,860 feet (870 m)	crossing
North Carolina: U.S. Route 21	2,692 feet (821 m)	crossing at Roaring Gap, NC
North Carolina: Thurmond Chatham Wildlife Management Area		triple point of New River and Yadkin/West Prong Roaring rivers
North Carolina: North Carolina Highway 105	4,020 feet (1,230 m)	crossing
North Carolina: North Carolina Highway 226 and Blue Ridge Parkway	2,820 feet (860 m)	crossing
North Carolina: Interstate 40	2,786 feet (849 m)	crossing
North Carolina: U.S. Route 74A	2,880 feet (880 m)	crossing
North Carolina: Interstate 26	2,130 feet (650 m)	crossing
North Carolina: U.S. Route 276	2,910 feet (890 m)	crossing
North Carolina: U.S. Route 178	2,694 feet (821 m)	crossing, approx. 1 mile north of NC/SC border
North Carolina–South Carolina: French Broad watershed		tributary of the Tennessee River along NC/SC border dividing mountain ridges running southeast meets Santee watershed flowing into Atlantic
North Carolina–South Carolina: Sassafras Mountain	3,564 feet (1,086 m)	located along the South Carolina-North Carolina border in northern Pickens County, South Carolina, and southern Transylvania County, North Carolina, nearest to the town of Rosman, North Carolina
North Carolina: U.S. Route 64	2,694 feet (821 m)	crossing
North Carolina–South Carolina: Savannah watershed		across the border of Pickens County, South Carolina & Greenville County, South Carolina, up into Transylvania County, North Carolina, Jackson County, North Carolina, and Macon County, North Carolina, to dividing mountain ridges to Tennessee River tributaries
North Carolina: North Carolina Highway 107	3,868 feet (1,179 m)	crossing
North Carolina: Cowee Gap	4,199 feet (1,280 m)	divides Tennessee (Cullasaja) and Savannah (Chatooga) rivers
North Carolina: Highlands, North Carolina	4,100 feet (1,200 m)	Sunset Rock
North Carolina: North Carolina Highway 28	3,771 feet (1,149 m)	crossing
Georgia: Black Rock Mountain State Park	3,640 feet (1,110 m)	a Blue Ridge summit
Georgia: ACF River Basin at Young Lick	3,809 feet (1,161 m)	triple point at intersection of 3 GA counties: Hiwassee (Towns Co)/Chattahoochee River (Habersham Co) on the west & on the east: Savannah River (Rabun Co)
Georgia: Altamaha watershed		triple point along border of Hall & Banks (GA) counties: Chattahoochee River-Banks (west) & Altamaha River-Hall/Savannah River-Banks (east)
Georgia: Suwanee watershed		triple point: Chattahoochee River/Suwanee Creek (west) & Altamaha River (east)
Georgia: Interstate 85	1,280 feet (390 m)	crossing (1 of 5)
Georgia: Interstate 85	1,120 feet (340 m)	crossing (2 of 5)
Georgia: Norcross, Georgia	1,086 feet (331 m)	through Norcross historic district
Georgia: Interstate 85	1,050 feet (320 m)	crossing (3 of 5)
Georgia: Interstate 285	1,020 feet (310 m)	crossing (1 of 2)
Georgia: Atlanta		near Dekalb Av
Georgia: Interstate 75/Interstate 85	1,020 feet (310 m)	crossing (1 of 4 crossings of I-75/4 of 5 crossings of I-85)
Georgia: Interstate 20	1,050 feet (320 m)	crossing
Georgia: Interstate 85	1,000 feet (300 m)	crossing (5 of 5)
Georgia: Interstate 75	976 feet (297 m)	crossing (2 of 4)
Georgia: Interstate 285	960 feet (290 m)	crossing (2 of 2)
Georgia: Interstate 75	927 feet (283 m)	crossing (3 of 4)
Georgia: Atlantic Seaboard fall line		near Macon, Georgia, this intersection is a triple physiographic point of the Piedmont (to the north) and the Gulf & Atlantic coastal plains (southwest & southeast).
Georgia: Interstate 75	410 feet (120 m)	crossing (4 of 4)
Georgia: Satilla watershed		triple point: Suwannee (west) & Altamaha River/Satilla River (east)
Georgia: St. Marys watershed		triple point: Suwannee (west) & Satilla River/St. Marys River (east)
Florida: St. Johns watershed		triple point: Suwannee (west) & St. Marys River/St. Johns River (east)
Florida: Interstate 10	159 feet (48 m)	crossing
Florida: Florida Trail		Central Florida crossing over the Florida crustal arch
Florida: Withlacoochee watershed		triple point: Suwannee/Withlacoochee River (Florida) (west) & St. Johns River (east)
Florida: Miami watershed		triple point: Withlacoochee (west) & St. Johns River/Miami River (east)
Florida: Kissimmee/Okeechobee watershed		south point of ECD @ Withlacoochee & Miami/Kissimmee triple point

See also

• Continental Divide of the Americas
• Great Basin Divide
• Laurentian Divide
• Saint Lawrence River Divide