Eastern Continental Divide
The Eastern Continental Divide, Eastern Divide or Appalachian Divide is a hydrographic 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 hydrographic divides of North America which define several drainage basins, each of which drains to a particular body of water.
The Eastern Continental Divide originates in the north at the Eastern Triple Divide in north-central Pennsylvania on the summit named 'Triple Divide Peak', 10.4 mi (16.7 km) south of the New York-Pennsylvania line, about 5 mi. southwest of the borough of Ulysses in Potter County, Pennsylvania. 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. Near Blacksburg, Virginia, the Divide deviates to the east along 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.
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, ending at the north bank watershed of the Kissimmee River at the northern boundary of the Lake Okeechobee Basin(see sidebar). While notionally, the ECD may be considered to extend to the southern tip of Florida, south of Lake Okeechobee the Everglades, which spans the length and breadth of the peninsula, is a seasonal swamp which drains into an unchannelled "river" 100 miles long and 60 miles wide that flows south to the Gulf of Mexico.
Though the divide is often associated with high elevation, at its southern terminus at the northern Kissimmee River watershed in Florida, the elevation is only 70ft. above sea level. Nor does the divide always coincide with the highest point or ridgeline, because streams can flow through passes or gaps in the ridge, so that terrain on one side of the ridge drains to the other side and therefore to the other watershed. This occurs in several places. The ECD is not completely fixed, but can shift due to erosion, tectonic shift and also anthropogenic activity such as tunnel excavation, damming of rivers and road construction.
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.
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.
|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)
|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)
|Virginia: Christiansburg, Virginia||2,180 feet (660 m)
||2940 Riner Rd, Christiansburg, VA 24073|
|Virginia: Interstate 77||2,860 feet (870 m)
|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)
|North Carolina: North Carolina Highway 226 and Blue Ridge Parkway||2,820 feet (860 m)
|North Carolina: Interstate 40||2,786 feet (849 m)
|North Carolina: U.S. Route 74A||2,880 feet (880 m)
|North Carolina: Interstate 26||2,130 feet (650 m)
|North Carolina: U.S. Route 276||2,910 feet (890 m)
|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||[specify]||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)
|North Carolina–South Carolina: Savannah watershed||[specify]||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)
|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)
|North Carolina: North Carolina Highway 28||3,771 feet (1,149 m)
|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||[specify]||triple point along border of Hall & Banks (GA) counties: Chattahoochee River-Banks (west) & Altamaha River-Hall/Savannah River-Banks (east)|
|Georgia: Suwanee watershed||[specify]||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||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)
|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||[specify]||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||[specify]||triple point: Suwannee (west) & Altamaha River/Satilla River (east)|
|Georgia: St. Marys watershed||[specify]||triple point: Suwannee (west) & Satilla River/St. Marys River (east)|
|Florida: St. Johns watershed||[specify]||triple point: Suwannee (west) & St. Marys River/St. Johns River (east)|
|Florida: Interstate 10||159 feet (48 m)
|Florida: Florida Trail||[specify]||Central Florida crossing over the Florida crustal arch|
|Florida: Withlacoochee watershed||[specify]||triple point: Suwannee/Withlacoochee River (Florida) (west) & St. Johns River (east)|
|Florida: Miami watershed||[specify]||triple point: Withlacoochee (west) & St. Johns River/Miami River (east)|
|Florida: Kissimmee/Okeechobee watershed||[specify]||south point of ECD @ Withlacoochee & Miami/Kissimmee triple point|
- "Triple Divide". Geographic Names Information System. United States Geological Survey.
- "PENNSYLVANIA'S MAJOR RIVER BASINS" (PDF). PA Department of Conservation and Natural Resources. Retrieved 2021-09-01.
- "Major River Watersheds of the Chesapeake Bay". www.cbf.org. Retrieved 2021-09-01.
- "Virginia's Major Watersheds". www.dcr.virginia.gov. Retrieved 2021-09-01.
- "North Carolina Watersheds". www.carolana.com. Retrieved 2021-09-01.
- "Georgia Rivers". Georgia River Network. Retrieved 2021-09-01.
- At headwaters of Boggy Creek just south of Orlando International Airport
- Alvin M. Josephy, Jr., ed. (1961). The American Heritage Book of Indians. The editors of American Heritage Magazine. American Heritage Publishing Co., Inc. LCCN 61-14871., pages 180-211, 188-189
- "Elevation Chart". The Great Allegheny Passage: The Cumberland and Pittsburgh Trail. Allegheny Trail Alliance. Archived from the original on May 6, 2009. Retrieved 2009-11-09. Maps: Eastern Continental Divide Archived 2010-05-15 at the Wayback Machine
- "Rock Mountain, GA - N34.91472° W83.34389°". www.topoquest.com.