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Eastern Continental Divide

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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. 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.

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.

Course

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Northern portion

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

The divide's northern portion winds through the middle of the Appalachian Mountains, either through the interior of the Allegheny Plateau or along the Allegheny Mountains. In this portion, the western drainage of the divide flows into the watersheds of the Allegheny River, Monongahela River, and New River, all tributaries of the Ohio River. The eastern drainage flows into the watersheds of the Susquehanna River, Potomac River, and James River, all of which flow into Chesapeake Bay before entering the Atlantic Ocean.

At its northern terminus, the Eastern Continental Divide originates at Triple Divide Peak[a] in Ulysses Township, Pennsylvania, about 10 mi (16 km) south of the New York-Pennsylvania border, where it diverges from the St. Lawrence Divide. This point divides the eastern United States into three watersheds: those of the Genesee River flowing into Lake Ontario and then the St. Lawrence River to the north; Pine Creek into the Susquehanna River as part of the Atlantic seaboard watershed to the east; and the Allegheny River into the Ohio, the Mississippi, 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.[2]

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.[3][4]

Central portion

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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.

The divide initially separates the headwaters of the New River from that of the Roanoke River.[3][4] 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.[5] 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

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

Past the southern end of the Appalachian Mountains, the divide's southern portion winds through the lowlands of Georgia and Florida. In this portion, the western drainage of the divide flows into the watersheds of the Apalachicola River, Suwannee River, Withlacoochee River, and Peace River, all of which drain directly to the Gulf of Mexico without reaching the Ohio River first. The eastern drainage flows into the watersheds of the Savannah River, Altamaha River, Satilla River, St. Marys River, and St. Johns River.

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. In southern Georgia, it separates the Suwannee River and Satilla River watersheds.[6]

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.

The southern terminus of the Eastern Continental Divide is at the triple divide between the St. Johns, Peace, and Kissimmee River watersheds, which is in Haines City, Florida on the Lake Wales Ridge.[7][8][9][10] Because the Kissimmee River flows into Lake Okeechobee, whose distributaries reach both the Gulf of Mexico and the Atlantic Ocean via low swampland covered by a network of diverging canals and natural waterways, its watershed's land is not clearly divisible between the two watersheds.[citation needed]

Weather

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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

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Prior to about 1760, north of Spanish Florida, the Appalachian Divide represented the boundary between British and French colonial possessions in North America. [11] 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.

Locations

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ECD points
Location State Coordinates Summit or other feature
Eastern Triple Divide Pennsylvania 2,523 feet (769 m)
41°50′48″N 77°50′14″W / 41.84667°N 77.83722°W / 41.84667; -77.83722
Triple Divide Peak, Ulysses Township, Potter County
I-80 41°07′13″N 78°38′05″W / 41.1202°N 78.6347°W / 41.1202; -78.6347
Babcock Ridge
Allegheny Mountain 2,167 feet (661 m)
40°28′53″N 78°33′01″W / 40.48139°N 78.55028°W / 40.48139; -78.55028
summit near Allegheny/Gallitzin Tunnels
2,690 feet (820 m)
39°57′41″N 78°51′24″W / 39.96139°N 78.85667°W / 39.96139; -78.85667
summit above Allegheny Mountain Tunnel (Pennsylvania Turnpike)
2,460 feet (750 m)
39°48′37″N 78°57′38″W / 39.81028°N 78.96056°W / 39.81028; -78.96056
summit above Sand Patch Tunnel
Savage Mountain 2,392 feet (729 m)[12]39°45′12″N 78°54′58″W / 39.75333°N 78.91611°W / 39.75333; -78.91611 railroad cut on Great Allegheny Passage
Pennsylvania/Maryland 2,840 feet (870 m)
39°43′21″N 78°54′51″W / 39.72250°N 78.91417°W / 39.72250; -78.91417
highest summit of the Mason–Dixon Line
I-68 Maryland 2,620 feet (800 m)
39°40′58″N 79°02′16″W / 39.6828°N 79.037704°W / 39.6828; -79.037704
crossing near Green Lantern Road
Savage Mountain 2,600 feet (790 m)
39°30′27″N 79°13′9″W / 39.50750°N 79.21917°W / 39.50750; -79.21917
saddle point at planned route of 1828 C&O Canal
Backbone Mountain Maryland/West Virginia 3,380 feet (1,030 m)
39°14′15″N 79°29′8″W / 39.23750°N 79.48556°W / 39.23750; -79.48556
(highest point)
Headwaters of Potomac River (Maryland's southern border) and Youghiogheny River
US 33 / WV 55 West Virginia 3,295 feet (1,004 m)
38°53′31″N 79°28′04″W / 38.892050°N 79.467781°W / 38.892050; -79.467781
Saddle Point at Pendleton County and Randolph County.
I-64 2,460 feet (750 m)
37°47′15″N 80°13′28″W / 37.787539°N 80.224528°W / 37.787539; -80.224528
Midland Trail: planned crossing for the 19th century James River and Kanawha Turnpike
Jefferson National Forest Virginia 3,620 feet (1,100 m)
37°20′27″N 80°32′4″W / 37.34083°N 80.53444°W / 37.34083; -80.53444
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)
Appalachian Trail 3,397 feet (1,035 m)
37°22′50″N 80°18′23″W / 37.380422°N 80.306368°W / 37.380422; -80.306368
Parallel Route Begin
Blacksburg, Virginia 2,080 feet (630 m)
Appalachian Trail 3,224 feet (983 m)
37°20′37″N 80°21′53″W / 37.343516°N 80.364647°W / 37.343516; -80.364647
Parallel Route Begin
I-81 2,180 feet (660 m)
37°07′43″N 80°22′17″W / 37.128708°N 80.371299°W / 37.128708; -80.371299
crossing
Christiansburg, Virginia 2,180 feet (660 m)
37°05′41″N 80°26′44″W / 37.094853°N 80.445558°W / 37.094853; -80.445558
2940 Riner Rd, Christiansburg, VA 24073
I-77 2,860 feet (870 m)
36°39′03″N 80°42′20″W / 36.650896°N 80.705609°W / 36.650896; -80.705609
crossing
US 21 / Blue Ridge Parkway North Carolina 2,692 feet (821 m)
36°23′47″N 80°59′11″W / 36.396259°N 80.986289°W / 36.396259; -80.986289
crossing at Roaring Gap, NC
Thurmond Chatham Wildlife Management Area 36°22′38″N 81°13′15″W / 36.377344°N 81.220722°W / 36.377344; -81.220722 triple point of New River and Yadkin/West Prong Roaring rivers
US 321 at Blowing Rock, North Carolina 3,620 feet (1,100 m)
36°07′06″N 81°39′38″W / 36.11844°N 81.66065°W / 36.11844; -81.66065
crossing at the Green Park Inn
NC 105 4,020 feet (1,230 m)
36°07′05″N 81°50′19″W / 36.118190°N 81.838560°W / 36.118190; -81.838560
crossing
NC 226 and Blue Ridge Parkway 2,820 feet (860 m)
35°51′10″N 82°03′03″W / 35.85266°N 82.0507166°W / 35.85266; -82.0507166
crossing
I-40 2,786 feet (849 m)
35°37′06″N 82°15′47″W / 35.618233°N 82.263007°W / 35.618233; -82.263007
crossing
US 74A 2,880 feet (880 m)
35°29′20″N 82°21′30″W / 35.488843°N 82.358308°W / 35.488843; -82.358308
crossing
I-26 2,130 feet (650 m)
35°17′24″N 82°24′07″W / 35.290048°N 82.40193°W / 35.290048; -82.40193
crossing
US 276 2,910 feet (890 m)
35°07′47″N 82°38′21″W / 35.129807°N 82.63921°W / 35.129807; -82.63921
crossing
US 178 2,694 feet (821 m)
35°05′46″N 82°48′34″W / 35.096133°N 82.80940°W / 35.096133; -82.80940
crossing, approx. 1 mile north of NC/SC border
French Broad watershed North Carolina–South Carolina [specify] tributary of the Tennessee River along NC/SC border dividing mountain ridges running southeast meets Santee watershed flowing into Atlantic
Sassafras Mountain 3,564 feet (1,086 m)
35°03′53″N 82°46′38″W / 35.06472°N 82.77722°W / 35.06472; -82.77722
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
US 64 North Carolina 2,694 feet (821 m)
35°07′32″N 82°54′39″W / 35.125507°N 82.910831°W / 35.125507; -82.910831
crossing
Savannah watershed North Carolina–South Carolina [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
NC 107 North Carolina 3,868 feet (1,179 m)
35°07′23″N 83°06′59″W / 35.12306°N 83.11639°W / 35.12306; -83.11639
crossing
Cowee Gap 4,199 feet (1,280 m)
35°05′27″N 83°08′52″W / 35.09083°N 83.14778°W / 35.09083; -83.14778
divides Tennessee (Cullasaja) and Savannah (Chatooga) rivers
Highlands, North Carolina 4,100 feet (1,200 m)
35°2′48.0408″N 83°11′13.434″W / 35.046678000°N 83.18706500°W / 35.046678000; -83.18706500
Sunset Rock
NC 28 3,771 feet (1,149 m)
35°02′27″N 83°12′08″W / 35.040808°N 83.202295°W / 35.040808; -83.202295
crossing
Black Rock Mountain State Park Georgia 3,640 feet (1,110 m)
34°54′53″N 83°20′38″W / 34.91472°N 83.34389°W / 34.91472; -83.34389[13]
a Blue Ridge summit
ACF River Basin at Young Lick 3,809 feet (1,161 m)
34°49′22″N 83°39′09″W / 34.82278°N 83.65250°W / 34.82278; -83.65250
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)
Altamaha watershed [specify] triple point along border of Hall & Banks (GA) counties: Chattahoochee River-Banks (west) & Altamaha River-Hall/Savannah River-Banks (east)
Suwanee watershed [specify] triple point: Chattahoochee River/Suwanee Creek (west) & Altamaha River (east)
I-85 1,280 feet (390 m)
34°04′31″N 83°55′04″W / 34.075235°N 83.917737°W / 34.075235; -83.917737
crossing (1 of 5)
I-85 1,120 feet (340 m)
33°59′53″N 84°04′36″W / 33.998098°N 84.07661°W / 33.998098; -84.07661
crossing (2 of 5)
Norcross, Georgia 1,086 feet (331 m)
33°56′44″N 84°12′46″W / 33.94558°N 84.21264°W / 33.94558; -84.21264
through Norcross historic district
I-85 1,050 feet (320 m)
33°54′44″N 84°12′29″W / 33.912202°N 84.207973°W / 33.912202; -84.207973
crossing (3 of 5)
I-285 1,020 feet (310 m)
33°48′11″N 84°15′00″W / 33.803115°N 84.250031°W / 33.803115; -84.250031
crossing (1 of 2)
Atlanta near Dekalb Av
I-75 / I-85 1,020 feet (310 m)
33°45′08″N 84°22′46″W / 33.752354°N 84.37942°W / 33.752354; -84.37942
crossing (1 of 4 crossings of I-75/4 of 5 crossings of I-85)
I-20 1,050 feet (320 m)
33°44′28″N 84°24′38″W / 33.741221°N 84.410663°W / 33.741221; -84.410663
crossing
I-85 1,000 feet (300 m)
33°39′42″N 84°25′39″W / 33.661782°N 84.4274°W / 33.661782; -84.4274
crossing (5 of 5)
I-75 976 feet (297 m)
33°39′19.60″N 84°23′42.52″W / 33.6554444°N 84.3951444°W / 33.6554444; -84.3951444
crossing (2 of 4)
I-285 960 feet (290 m)
33°37′51.56″N 84°23′34.40″W / 33.6309889°N 84.3928889°W / 33.6309889; -84.3928889
crossing (2 of 2)
I-75 927 feet (283 m)
33°34′29.77″N 84°20′7.67″W / 33.5749361°N 84.3354639°W / 33.5749361; -84.3354639
crossing (3 of 4)
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).
I-75 410 feet (120 m)
32°10′16.10″N 83°45′9.25″W / 32.1711389°N 83.7525694°W / 32.1711389; -83.7525694
crossing (4 of 4)
Satilla watershed [specify] triple point: Suwannee (west) & Altamaha River/Satilla River (east)
St. Marys watershed [specify] triple point: Suwannee (west) & Satilla River/St. Marys River (east)
St. Johns watershed Florida [specify] triple point: Suwannee (west) & St. Marys River/St. Johns River (east)
I-10 159 feet (48 m)
30°15′14.64″N 82°23′57.84″W / 30.2540667°N 82.3994000°W / 30.2540667; -82.3994000
crossing
Florida Trail [specify] Central Florida crossing over the Florida crustal arch
Withlacoochee watershed [specify] triple point: Suwannee/Withlacoochee River (Florida) (west) & St. Johns River (east)
Miami watershed [specify] triple point: Withlacoochee (west) & St. Johns River/Miami River (east)
Kissimmee/Okeechobee watershed [specify] south point of ECD @ Withlacoochee & Miami/Kissimmee triple point

See also

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Notes

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References

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  1. ^ "Triple Divide". Geographic Names Information System. United States Geological Survey, United States Department of the Interior.
  2. ^ "PENNSYLVANIA'S MAJOR RIVER BASINS" (PDF). PA Department of Conservation and Natural Resources. Archived from the original (PDF) on 2021-09-01. Retrieved 2021-09-01.
  3. ^ a b "Major River Watersheds of the Chesapeake Bay". www.cbf.org. Retrieved 2021-09-01.
  4. ^ a b "Virginia's Major Watersheds". www.dcr.virginia.gov. Retrieved 2021-09-01.
  5. ^ "North Carolina Watersheds". www.carolana.com. Retrieved 2021-09-01.
  6. ^ "Georgia Rivers". Georgia River Network. Retrieved 2021-09-01.
  7. ^ "Palatlakaha River Watershed". Polk County Water Atlas. Retrieved 2024-12-17.
  8. ^ "Peace River - Peace Creek Canal Watershed". Polk County Water Atlas. Retrieved 2024-12-17.
  9. ^ "Kissimmee River - Above Lake Hatchineha Watershed". Polk County Water Atlas. Retrieved 2024-12-17.
  10. ^ Palmer, Tom (2020-08-22). "Nature of Things: Lake Lowery flooding has no easy solution". The Ledger. Retrieved 2024-12-17.
  11. ^ 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
  12. ^ "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
  13. ^ "Rock Mountain, GA - N34.91472° W83.34389°". www.topoquest.com.