The fall line has meanings in both geographical features and the sport of alpine skiing.

Geographical fall line

As a geographical feature, the fall line marks the area where an upland region (continental bedrock) and a coastal plain (coastal alluvia) meet. The fall line is typically prominent where a river crosses it, for there will usually be rapids or waterfalls. Because of these features river boats typically can not travel any further inland. Because of the need of a port, and ready supply of water power, settlements often developed where the river crosses the fall line.

The most prominent example of fall line settlement was the establishment of the cities along the eastern coast of the United States where the Appalachian Rise and the coastal plains meet. Cities on this fall line, from north to south, include:

• Boston, Massachusetts
• Pawtucket, Rhode Island
• Troy, New York
• Trenton, New Jersey
• Washington, D.C. (originally Georgetown in Maryland)
• Fredericksburg, Virginia
• Richmond, Virginia
• Petersburg, Virginia
• Roanoke Rapids, North Carolina
• Raleigh, North Carolina
• Columbia, South Carolina
• Augusta, Georgia

U.S. Highway 1 and Interstate 95 passes through most of these cities.

• Virginia Places website page on Rivers and Fall Line Cities provides a more detailed explanation of why some towns and cities along a Fall line grew and others did not.

Alpine skiing fall line

In alpine skiing, a fall line refers to the line down a mountain or hill which is most directly downwards. This can be visualized as the route a ball would take if it were started rolling at the summit, and rolled to the bottom. This route (within the constraints of ski runs), is the optimal route down a run for a downhill skier.