Eastern Continental Divide


The Eastern Continental Divide or 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 divide originates at the Eastern Triple Divide near the middle of the northern border of Pennsylvania then runs generally south-by-southwest following the crest of the Appalachian Mountains through Pennsylvania, western Maryland, West Virginia, Virginia and North Carolina to its high point on Grandfather Mountain, then descends to the city of Atlanta in northwestern Georgia, where it doglegs southeasterly across the Georgia plateau and through the lowlands of Northern Florida to its terminus in central Florida at the northern boundary of the Lake Okeechobee Basin.
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.
In colonial times, except for Spanish Florida, the ECD served as the boundary between English colonies on the Atlantic seaboard and Indian lands to the interior.

Description


Eastern Triple Divide

The Eastern Triple Divide is the northern terminus of the Eastern Continental Divide where it intersects the northeasterly St. Lawrence Divide near the middle of the northern border of Pennsylvania. That point divides the eastern United States into three watersheds, where the associated nearby headwaters form the Pine Creek tributary of West Branch Susquehanna River that drains to the Atlantic ocean, the Allegheny River tributary of the Ohio River that drains to the Gulf of Mexico, and the Genesee River tributary of Lake Ontario that drains to the Gulf of Saint Lawrence.

The Eastern Continental Divide originates in the north at the Eastern Triple Divide on the summit named 'Triple Divide Peak' 10.4 mi south of the New York-Pennsylvania line about 5 mi. southwest of the borough of Ulysses in Potter County, Pennsylvania. That summit is the northernmost peak of three atop a broad plateau which is currently farmland. From there, the ECD runs south-southwest through the two nearby southern summits then southwesterly along the Allegheny Plateau west of the Allegheny Front until it plunges south along the Appalachians barrier ridge. Mount Mitchell State Park in North Carolina is the highest point on the ECD at 6,366 ft. As the altitude of the peaks diminishes across the swampy Georgia plateau, the divide meanders into the low country of Northern Florida until it reaches central Florida, ending at the north bank watershed of the Kissimmee River.
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 the lake. During the wet season, overflow from the lake forms an unchanneled "river" 100 miles long and 60 miles wide that flows south to Florida Bay which ostensibly drains into the Gulf of Mexico, but due to mud dykes, little exchange of water actually occurs. So hydrographically, the only divide in southern Florida is between the lake and the ocean or Gulf, and that divide is coincident with the boundary between land and sea.
Because the divide represents 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.

Lake Okeechobee Basin

The Lake Okeechobee drainage basin in south central Florida, including the Kissimmee River drainage basin to the north which feeds it, was naturally or hydrographically, an endorheic basin, one which does not have outflow to another body of water like a river or ocean. Such a basin may form a swamp when water collects. It was altered by anthropogenic activity, specifically the construction of the Okeechobee canal in 1937 which spanned the Atlantic Ocean, the lake and the Gulf of Mexico. Nonetheless, it is not considered by hydrologists to be part of either the Gulf of Mexico watershed or Atlantic seaboard watershed. The northern boundary of the basin is the southern terminus of the Eastern Continental divide.

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.

Locations

AreaPointSummit or other feature
Pennsylvania:
Triple Divide Peak, Ulysses Township, Potter County
Pennsylvania: Babcock Ridge
Pennsylvania: Allegheny Mountain
summit near Allegheny/Gallitzin Tunnels
Pennsylvania: Allegheny Mountain
summit above Allegheny Mountain Tunnel
Pennsylvania: Allegheny Mountain
summit above Sand Patch Tunnel
Pennsylvania: Savage Mountainrailroad cut on Great Allegheny Passage
Pennsylvania/Maryland: Savage Mountain
highest summit of the Mason–Dixon Line
Maryland: Interstate 68
crossing near Green Lantern Road
Maryland: Savage Mountain
saddle point at planned route of 1828 C&O Canal
Maryland/West Virginia: Backbone Mountain

Headwaters of Potomac River and Youghiogheny River
West Virginia: US Route 33 / State Route 55
Saddle Point at Pendleton County and Randolph County.
West Virginia: Interstate 64
Midland Trail: planned crossing for the 19th century James River and Kanawha Turnpike
Virginia: Jefferson National Forest
saddle point at Johns Creek headwaters, and near triple point of Mississippi River & Chesapeake Bay /Albemarle Sound
Virginia: Appalachian Trail
Parallel Route Begin
Virginia: Blacksburg, Virginia
Virginia: Appalachian Trail
Parallel Route Begin
Virginia: Interstate 81
crossing
Virginia: Christiansburg, Virginia
2940 Riner Rd, Christiansburg, VA 24073
Virginia: Interstate 77
crossing
North Carolina: U.S. Route 21
crossing at Roaring Gap, NC
triple point of New River and Yadkin/West Prong Roaring rivers
North Carolina: North Carolina Highway 105
crossing
North Carolina: North Carolina Highway 226 and Blue Ridge Parkway
crossing
North Carolina: Interstate 40
crossing
North Carolina: U.S. Route 74A
crossing
North Carolina: Interstate 26
crossing
North Carolina: U.S. Route 276
crossing
North Carolina: U.S. Route 178
crossing, approx. 1 mile north of NC/SC border
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
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
crossing
North Carolina–South Carolina: Savannah watershedacross 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: Highlands, North Carolina
Sunset Rock
North Carolina: North Carolina Highway 28
crossing
North Carolina: Cowee Gap
divides Tennessee and Savannah rivers
Georgia: Black Rock Mountain State Park
a Blue Ridge summit
Georgia: ACF River Basin at Young Lick
triple point at intersection of 3 GA counties: Hiwassee /Chattahoochee River on the west & on the east: Savannah River
Georgia: Altamaha watershedtriple point along border of Hall & Banks counties: Chattahoochee River-Banks & Altamaha River-Hall/Savannah River-Banks
Georgia: Suwanee watershedtriple point: Chattahoochee River/Suwanee Creek & Altamaha River
Georgia: Interstate 85
crossing
Georgia: Interstate 85
crossing
Georgia: Norcross, Georgiathrough Norcross historic district
Georgia: Interstate 85
crossing
Georgia: Interstate 285
crossing
Georgia: Atlantanear Dekalb Av
Georgia: Interstate 75/Interstate 85
crossing
Georgia: Interstate 20
crossing
Georgia: Interstate 85
crossing
Georgia: Interstate 75
crossing
Georgia: Interstate 285
crossing
Georgia: Interstate 75
crossing
Georgia: Atlantic Seaboard fall linenear Macon, Georgia, this intersection is a triple physiographic point of the Piedmont and the Gulf & Atlantic coastal plains.
Georgia: Interstate 75
crossing
Georgia: Satilla watershedtriple point: Suwannee & Altamaha River/Satilla River
Georgia: St. Marys watershedtriple point: Suwannee & Satilla River/St. Marys River
Florida: St. Johns watershedtriple point: Suwannee & St. Marys River/St. Johns River
Florida: Interstate 10
crossing
Florida: Florida TrailCentral Florida crossing over the Florida crustal arch
Florida: Withlacoochee watershedtriple point: Suwannee/Withlacoochee River & St. Johns River
Florida: Miami watershedtriple point: Withlacoochee & St. Johns River/Miami River
Florida: Kissimmee/Okeechobee watershedsouth point of ECD @ Withlacoochee & Miami/Kissimmee triple point