The Middle Atlantic Coastal Plain ecoregion stretches from extreme southern New Jersey to South Carolina and almost to the Georgia border. This ecoregion consists of low elevation flat plains, with numerous barrier islands, beaches, esturaries, dunes, marshes, swamps.

These low terraces flat plains are underlain by loosely arranged and unsolidified sediments, with poorly drained soils being common. This ecoregion has a mix of coarse and finer textured soils compared to the mostly coarse soils in the majority of Southern Coastal Plain ecoregion (12S) which lies along the continental coast to the south.

Too, the Middle Atlantic Coastal Plain is typically lower in elevation, flatter, more poorly drained, and more marshy than that coastal ecoregion to the south. Notably, less cropland occurs in the southern portion of this ecoregion than in the central and northern parts.

When compared to the mainly longleaf-slash pine forests of the warmer Southern Coastal Plain (12S), the forest cover in this ecoregion was once dominated by longleaf pine, especially in the Carolinas, but now is mostly loblolly and some shortleaf pine, with patches of oak, gum, and cypress near major streams,

Assateague National Seashore