Atlantic Seaboard fall line
Escarpment
Map showing part of the Eastern Seaboard Fall Line where the pale-colored coastal plain meets the brightly colored Piedmont.
Location	United States
Formed by	New Jersey,Virginia, theCarolinas, andGeorgia, U.S.[1][2]
Dimensions
• Length	900 mi (1,400 km)[2]

TheAtlantic Seaboard Fall Line, orFall Zone, is a 900-mile (1,400 km)escarpment where thePiedmont andAtlantic coastal plain meet in theeastern United States.^[2] Much of the Atlantic Seaboard fall line passes through areas where no evidence offaulting is present.

Thefall line marks the geologic boundary of hard metamorphosed terrain—the product of theTaconic orogeny—and the sandy, relatively flatalluvial plain of the upper continental shelf, formed of unconsolidatedCretaceous andCenozoicsediments. Examples of Fall Zone features include thePotomac River's Little Falls and the rapids inRichmond, Virginia, where theJames River falls across a series of rapids down to its own tidal estuary.

Before navigation improvements, such as locks, the fall line was generally thehead of navigation on rivers due to their rapids or waterfalls, and the necessaryportage around them. Numerous cities initially formed along the fall line because of the easy river transportation to seaports, as well the availability of water power to operate mills and factories, thus bringing together river traffic and industrial labor.U.S. Route 1 andI-95 link many of the fall-line cities.

In 1808,Treasury SecretaryAlbert Gallatin noted the significance of the fall line as an obstacle to improved national communication and commerce between the Atlantic seaboard and the western river systems:^[3]

The most prominent, though not perhaps the most insuperable obstacle in the navigation of the Atlantic rivers, consists in their lower falls, which are ascribed to a presumed continuous granite ridge, rising about one hundred and thirty feet above tide water. That ridge from New York to James River inclusively arrests the ascent of the tide; the falls of every river within that space being precisely at the head of the tide; pursuing thence southwardly a direction nearly parallel to the mountains, it recedes from the sea, leaving in each southern river an extent of good navigation between the tide and the falls. Other falls of less magnitude are found at the gaps of theBlue Ridge, through which the rivers have forced their passage...

Some cities that lie along the Piedmont–Coastal Plain fall line include the following (from north to south):

• New Brunswick, New Jersey on theRaritan River
• Princeton, New Jersey, on theMillstone River
• Trenton, New Jersey, on theDelaware River.^[2]
• Philadelphia, Pennsylvania, on theSchuylkill River.^[4]
• Wilmington, Delaware, on theBrandywine River.
• Perryville, Maryland, andHavre de Grace, Maryland, on theSusquehanna River/head ofChesapeake Bay.
• Baltimore, Maryland, onHerring Run,Jones Falls, andGwynns Falls.^[5]
• Elkridge, Maryland, on thePatapsco River.^{[citation needed]}
• Laurel, Maryland, on thePatuxent River.^{[citation needed]}
• Washington, D.C., on thePotomac River.^[6]
• Occoquan, Virginia, on theOccoquan River.^{[citation needed]}
• Fredericksburg, Virginia on theRappahannock River.^[6]
• Richmond, Virginia, on theJames River.^[7]
• Petersburg, Virginia, on theAppomattox River.^[8]
• Weldon, North Carolina, andRoanoke Rapids, North Carolina, on theRoanoke River^[9]
• Rocky Mount, North Carolina, on theTar River.^[9]
• Kinston,Smithfield, andGoldsboro, North Carolina, on theNeuse River.^[9]
• Fayetteville, North Carolina, on theCape Fear River.^[9]
• Lumberton, North Carolina, on theLumber River.^[9]
• Cheraw, South Carolina, on thePee Dee River.^{[citation needed]}
• Camden, South Carolina, on theWateree River.^{[citation needed]}
• Columbia, South Carolina, on theCongaree River.^[7]
• Augusta, Georgia, on theSavannah River.^[10]
• Milledgeville, Georgia, on theOconee River.^[10]
• Macon, Georgia, on theOcmulgee River.^[10]
• Columbus, Georgia, on theChattahoochee River.^[2]
• Tallassee, Alabama, on theTallapoosa River^[11]
• Wetumpka, Alabama, on theCoosa River^[11]
• Tuscaloosa, Alabama, on theBlack Warrior River^[11]

This list isincomplete; you can help byadding missing items.(June 2010)

• East Coast of the United States
• Escarpments of the United States

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