Atlantic Seaboard Fall Line

09/08/25

“What marks the end of the eastern coastal plain in the U.S.?”

The US Eastern Seaboard from New York City down to Georgia is dominated by the Atlantic coastal plain. The Atlantic Seaboard Fall Line escarpment marks the border between the coastal plain and the foothills of Appalachia. Around this border are some of the most populous cities in the Eastern US, such as Philadelphia, Washington DC, and Richmond. Rivers going through this fall line usually develop rapids or waterfalls when they reach the border, making cross-border navigation difficult. Many cities were settled along the Atlantic Seaboard fall line because they could trade with cities above and below the rapid descent of their rivers.