The major mountain range that lies to the west of the Atlantic Coastal Plain is Appalachian Mountains.

The Appalachian Mountains are the major mountain range located to the west of the Atlantic Coastal Plain. Stretching from Canada to central Alabama, the Appalachians serve as a significant natural boundary for the Coastal Plain region. This range features diverse landscapes, including rolling hills, rugged peaks, and deep valleys, which contrast sharply with the flat terrain of the Coastal Plain. The Appalachians are not only vital for their geological significance but also play a crucial role in the region’s ecology, influencing climate patterns and providing habitats for various wildlife species. Their cultural and historical importance adds to the rich tapestry of the Atlantic Coastal Plain.