fall line

American  

noun

1. an imaginary line, marked by waterfalls and rapids, where rivers descend abruptly from an upland to a lowland.

2. Fall Line, (in the eastern United States) the imaginary line between the Piedmont and the Atlantic coastal plain.

3. Skiing. the path of natural descent from one point on a slope to another.

---

Fall Line ¹ British  

noun

1. a natural junction, running parallel to the E coast of the US, between the hard rocks of the Appalachians and the softer coastal plain, along which rivers form falls and rapids

---

fall line ² British  

noun

1. skiing the natural downward course between two points on a slope

2. the edge of a plateau

---

fall line Scientific  

/ fôl /

1. A line connecting the waterfalls of nearly parallel rivers that marks a drop in land level.

---

Etymology

Origin of fall line

An Americanism dating back to 1880–85

Example Sentences

The racer is traversing the hill perpendicular to the fall line, almost moving in an upward direction.

From Los Angeles Times • Feb. 9, 2026

The sprawling resort does not have a single fall line from the top, but rather folds into multiple zones served by chairlifts nestled in basins, so navigation can prove confusing.

From Seattle Times • Mar. 19, 2022

On Thursday, a Netflix spokesperson said the company was raising prices “so that we can continue to offer more variety of TV shows and films - in addition to our great fall line up.”

From Reuters • Oct. 29, 2020

While the Powhatan Indians ruled Virginia’s Tidewater region, the Monacans held sway from the fall line west to the Blue Ridge Mountains.

From Washington Post • Jan. 5, 2020

This led to a long struggle between coast and interior, terminated only when the slave population passed across the fall line, and more nearly assimilated coast and up-country.

From The Frontier in American History by Turner, Frederick Jackson