The Eastern Continental Divide, Eastern Divide or Appalachian Divide is a hydrological divide in eastern North America that separates the easterly Atlantic Seaboardwatershed from the westerly Gulf of Mexico watershed. It 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.
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.<ref>Template:Cite web</ref>
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.<ref name=":0" /><ref name=":1" />
Central portion
The divide's central portion generally follows the easternmost ridge of the Blue Ridge Mountains and thus of the Appalachian Mountains as a whole, which takes the form of a high escarpment. In this portion, the western drainage of the divide flows into the watersheds of the New River and Tennessee River, both tributaries of the Ohio River. The eastern drainage flows into the watersheds of the Roanoke River, Pee Dee River, and Santee River.<ref name=":2">Template:Cite web</ref>
The divide initially separates the headwaters of the New River from that of the Roanoke River.<ref name=":0">Template:Cite web</ref><ref name=":1">Template:Cite web</ref> 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.<ref name=":2" /><ref>Template:Cite web</ref> Its high point is on Grandfather Mountain at 5,946 feet (1,812 m); although Mount Mitchell is the highest point in the Appalachian Mountains, it is not on the Divide, but 4 miles west of it.
Southern portion
A monument marking the Eastern Continental Divide that shows where the watershed drains, located on the Duluth Town Green in Duluth, Georgia
In Florida, the Divide generally follows the western edge of the St. Marys River and then St. Johns River, meandering into the low country of Northern Florida until it reaches Central Florida. The west side of the divide continues to be the Suwannee River and then the Withlacoochee River watersheds.
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.
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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.
The exact route of the ECD shifts over time due to erosion, tectonic activity, construction projects, and other factors.
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