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TheGreat Appalachian Valley, also calledThe Great Valley orGreat Valley Region, is one of the major landform features of easternNorth America. It is a gigantic trough, including a chain of valley lowlands, and the central feature of theAppalachian Mountains system. The trough stretches about 1,200 miles (1,900 km) fromQuebec in the north toAlabama in the south and has been an important north–south route of travel since prehistoric times.

The Great Valley marks the eastern edge of theRidge and Valleyphysiographic province. There are many regional names of the Great Valley, such as the Shenandoah Valley. From a large perspective the Great Valley can be divided into a northern section and a southern section.

In its northern section, the Great Valley includes theChamplain Valley aroundLake Champlain and the upperRichelieu River that drains it into theSaint Lawrence, theHudson River Valley,Newburgh Valley, andWallkill Valley, and theKittatinny Valley,Upper Delaware River Valley,Lebanon Valley, andCumberland Valley.

A series of mountains bounds the northern half of the Great Valley on both sides. To the east or coastward side, these include, from north to south, theGreen Mountains ofVermont, theTaconic Mountains of Vermont,New York,Massachusetts, andConnecticut, theReading Prong, which includes theNew York–New Jersey Highlands, also known as theHudson Highlands,Schunemunk Mountain, andRamapo Mountains, andSouth Mountain inPennsylvania beyondHarrisburg. There is a wide gap between the Reading Prong and South Mountain at Harrisburg, through which theSusquehanna River passes, connecting the Great Valley with thePiedmont region of southeast Pennsylvania. This gap is often considered the dividing point between the northern and southern sections of the Great Valley.

To the west or continental side, a series of more impenetrable mountain regions border the northern Great Valley. The northernmost is theAdirondack Mountains, a southern extension of theCanadian Shield, which reach the valley along the shores ofLake Champlain andLake George. To their south, beyond theMohawk Valley andAlbany, New York, theCatskill Mountains, which form the northeastern terminus of theAllegheny Plateau, border the valley in the form of the dramaticCatskill Escarpment, which overlooks the middle reaches of theHudson River andHudson Valley. Just south of the Catskills, the first folds of theRidge-and-Valley Appalachians border the valley, in the form of a continuous ridge (heading south) and known as theShawangunk Ridge in New York,Kittatinny Mountain inNew Jersey, andBlue Mountain inPennsylvania. This long ridge is broken by several narrow and dramatic gaps, known aswind andwater gaps, including Culver's Gap in New Jersey, theDelaware Water Gap, where theDelaware River passes into theLehigh Valley along the border between New Jersey and Pennsylvania, and many gaps in Pennsylvania, including thePennsylvania Wind Gap, theLehigh River Gap north ofAllentown, theSchuylkill River Gap, theSwatara Gap, theSusquehanna River Gap, and others.

In its southern section, the Great Valley is bounded to the east by theBlue Ridge Mountains, which extend north intoMaryland andPennsylvania asSouth Mountain. Regional names of the southern Great Valley includeHagerstown Valley inMaryland, Winchester Valley, andShenandoah Valley inVirginia andWest Virginia, the upper valley of theJames River,Roanoke Valley, andNew River Valley in Virginia, theHolston River Valley in Virginia andTennessee, and the EastTennessee Valley extending from Virginia through Tennessee toAlabama. TheCoosa River Valley is often considered the southernmost part of the Great Valley. These southern portions of the Great Valley are sometimes grouped into two parts, the Valley of Virginia and theTennessee Valley.

The southern Great Valley is bounded on the east by the Blue Ridge physiographic province, which includes, from north to south, South Mountain in Pennsylvania and Maryland, the Blue Ridge of Virginia,Holston Mountain in Tennessee, and theUnaka Range and theGreat Smoky Mountains of Tennessee andNorth Carolina. A gap in these mountains exists nearRoanoke, Virginia. Other gaps of note in the Blue Ridge of Virginia, connecting the Piedmont region with the Great Valley, includeThornton Gap,Swift Run Gap, andRockfish Gap.

Another series of mountains bounds the southern Great Valley to the west, includingNorth Mountain andGreat North Mountain, theAllegheny Front,Powell Mountain, theCumberland Mountains,Walden Ridge, and theCumberland Plateau. TheCumberland Gap connects the Great Valley region withKentucky and Tennessee lands to the west.Massanutten Mountain lies in the middle of the Valley of Virginia portion of the Great Valley. The Valley of Virginia is a region ofkarst, withsinkholes andcaverns.

The climate of the Great Valley is generallyWarm- or Hot-summer Humid continental in the northern third andHumid subtropical fromPennsylvania southward. The first weather box is from the temperate portion and the second subtropical portion of the valley.

Routes through the valley were first used byNative Americans. In pre-colonial and the earlycolonial era, a major Indian pathway through the Great Valley was known as theGreat Indian Warpath, Seneca Trail, and various other names.

For European colonists, the Great Valley was a major route for settlement and commerce in the United States along theGreat Wagon Road, which began inPhiladelphia. In the Shenandoah Valley, the road was known as theValley Pike. TheWilderness Road branched off from Great Wagon Road in present-dayRoanoke, Virginia, crossed theCumberland Gap and led toKentucky andTennessee, including the fertileBluegrass region andNashville Basin. Another branch at Roanoke, called theCarolina Road, led into thePiedmont regions ofNorth Carolina,South Carolina, andGeorgia.

The various gaps connecting the Great Valley to lands to the east and west have played important roles in American history. On the east side, the wide gap in southeastPennsylvania became the main route for colonization of the Great Valley. By the 1730s, the Pennsylvanian Great Valley west of South Mountain was open to settlement after treaty cessions and purchases from the Indians. The region drew a steady and growing stream of immigrants and became known as "the best poor man's country". European immigrants ultimately thoroughly settled the Great Valley in Pennsylvania and were rapidly migrating and settling southwards into the Shenandoah Valley ofVirginia. The entire region between southeast Pennsylvania and the Shenandoah Valley soon became famous as a breadbasket, the most productive mixed farming region in America (Meinig, 1986:134). The road fromPhiladelphia west to the valley and then south through it became very heavily used and known variously as the Great Wagon Road, the Philadelphia Wagon Road, and the Valley Road. TheConestoga wagon was developed around 1725 in the area of the wide opening between Philadelphia and the Great Valley. The Conestoga wagon became the main vehicle for transportation through the Great Valley until the railroad era.

Culver Gap nearCulver's Lake inSussex County, New Jersey, was an important route through theKittatinny Mountain from about 10,000 years ago to present. The gap is more than 400 feet (120 m) below the top of the mountain.Lenape Native Americans used the gap to hunt and trade on both sides of the mountain. Early settlers from Pennsylvania used the water drop from Culvers Lake toBranchville for a wide assortment of mills. Turnpikes followed the route of Lenape trails through the gap.

By the 1750s, the Great Valley was well-settled to the southern end of the Shenandoah Valley. Immigrants continued to travel from the Philadelphia area south through the Great Valley beyond Shenandoah, to the vicinity of present-dayRoanoke, Virginia. There is a wide gap in the Blue Ridge near Roanoke. A branch of the Great Wagon Road began there, crossing through the gap east into the Piedmont region ofNorth Carolina andSouth Carolina. This road became known as the Carolina Road. During the 1750s, the stream of migrants traveling south through the valley and into the Carolina Piedmont grew into a flood. At the time, the Carolina Piedmont region offered some of the best land at the lowest prices. A string of towns appeared, includingSalisbury,Salem, andCharlotte in North Carolina. In the decades before theAmerican Revolution, the Piedmont "upcountry" of the Carolinas was quickly settled, mostly by recent immigrants who migrated from the north to the south via the Great Valley. Many of these immigrants wereScots-Irish,Germans from theRhineland-Palatinate area, andMoravians. This upcountry population soon surpassed the older and more established lowcountry population near theAtlantic coast, causing serious geopolitical tensions in the Carolinas during the late 18th century (Meinig, 1986: 291–293).

On the west side, theCumberland Gap became the main route for migration west from the southern Great Valley toKentucky andTennessee. In the north, theMohawk Valley became a major route for westward expansion, especially after the construction of theErie Canal, which linkedNew York City in the east to theGreat Lakes region in theMidwest via theHudson River of the Great Valley and the Mohawk Valley gap.

The Great Valley, especially Shenandoah Valley, played an important role during theAmerican Civil War, including its Blue Ridge gaps and nearby Piedmont area and its northward extension toGettysburg, Pennsylvania, where the bloodiest and most influential Civil War battle was fought in theBattle of Gettysburg from July 1 to July 3, 1863. The Battle of Gettysburg resulted in over 50,000 casualties, but theUnion Army victory under the command of Major GeneralGeorge Meade over GeneralRobert E. Lee'sConfederate Army forces turned the war in theUnion's favor.

Civil War-era sites and events in this region includeHarpers Ferry, West Virginia;Antietam, Maryland;Chambersburg, Pennsylvania; theValley Campaign ofNorthern Virginia; theValley Campaigns of 1864, also in Virginia; theBattles of Chattanooga in Tennessee; and theGettysburg Battlefield andGettysburg National Cemetery in Pennsylvania.

Today, the main thoroughfares occupying thesouthern Great Valley are:

• I-81 fromHarrisburg, Pennsylvania to the road's southern terminus nearDandridge, Tennessee
• I-40 from the I-81 interchange toKnoxville
• I-75 from Knoxville toCleveland, Tennessee

In thenorthern valley, the thoroughfares vary. Heading northeast from Harrisburg, I-81 traces the valley toSwatara Gap, then swings north acrossBlue Mountain and leaves the valley en route toScranton.I-78 then continues the route through the valley parallel to the southern slopes of Blue Mountain, connecting Harrisburg withLebanon,Kutztown, andAllentown. At Allentown, I-78 then swings away south into the hills of theReading Prong en route toNew York City. From Allentown into New Jersey and southern New York, the valley is not traced by an interstate highway, though it is traversed at length (and at oblique angles) by bothI-80 andI-84, as well as by theDelaware River betweenEaston, Pennsylvania, and theDelaware Water Gap.

In New Jersey and New York, the valley gradually bends from the northeast to the north, and starting nearNewburgh just beyond theHudson Highlands,I-87 runs much of the valley's length into Canada, passingPoughkeepsie,Albany, andGlens Falls. In an east–west section of the valley,I-90 traverses theMohawk Valley towardsUtica. North of Glens Falls, I-87 runs west of the valley through theAdirondack Mountains, though it descends back into the valley nearPlattsburgh. At the Canada–US border, I-87 becomesAutoroute 15 and continues north toMontreal. No interstate highway crosses the rugged section of the valley east ofLake George or passes through the agriculturally richChamplain Valley running north toBurlington, Vermont.

Heading north from Burlington, however, along the east side ofLake Champlain,I-89 runs through the valley's northernmost stretches to the Canada–US border, where it becomesQuebec Route 133 andAutoroute 35, which trace the route of theRichelieu River in its southern section, where the Great Valley finally dissipates into the plain of theSaint Lawrence River to the east of Montreal. (The Richelieu River continues northward across the plain and empties into the Saint Lawrence to the northeast of Montreal.)

The Great Valley, especially the southern-middle portion, is within the region known asAppalachia.

• Martinsburg Formation

• Appalachian Topography – Paleontological Research Institution
• Appalachian Mountains – Columbia Gazetteer of North America
• USGS – Valley and Ridge Province
• Pennsylvania Geology Map
• Geological Structure of Pennsylvania
• Drake, Richard B. (2001),A History of Appalachia. Lexington: The University Press of Kentucky.ISBN 0-8131-2169-8
• Kercheval, Samuel (1850),A History of the Valley of Virginia,Woodstock, Virginia – History (much of it anecdotal) of the colonial Virginia northern frontier
• Meinig, D. W. (1986),The Shaping of America: A Geographical Perspective on 500 Years of History, Volume 1:Atlantic America, 1492–1800. New Haven:Yale University Press.ISBN 0-300-03882-8
• Williams, John Alexander (2002),Appalachia: A History. Chapel Hill: University of North Carolina Press.ISBN 0-8078-5368-2

39°30′N77°50′W / 39.500°N 77.833°W /39.500; -77.833

• Appalachian Mountains
• Eastern United States
• East Tennessee
• Geography of Appalachia
• History of United States expansionism
• Landforms of New Hampshire
• Landforms of South Carolina
• Geography of the Lehigh Valley
• Regions of Pennsylvania
• Regions of the United States
• Regions of Virginia
• Valleys of Alabama
• Valleys of Georgia (U.S. state)
• Valleys of Maryland
• Valleys of New Jersey
• Valleys of New York (state)
• Valleys of Pennsylvania
• Valleys of Tennessee
• Valleys of the United States
• Valleys of Virginia
• Western Maryland

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