The Upper East Gulf Coastal Plain ecoregion encompasses 33,861,051 acres or 52,908 square miles. The region ranges from southern Illinois, western Kentucky and Tennessee, throughout much of Mississippi, east to Alabama and a limited area of Georgia, and southeastern Louisiana. The region is bounded on the west by the Mississippi River Alluvial Plain and on the north by the Ohio River, and Tennessee River (now Kentucky Lake). The eastern margin occurs at the contact point with older rocks of the Piedmont and Southern Ridge and Valley. The southern margin of the region is perhaps the least obvious on the ground, but represents the boundary between the middle and outer coastal plain of Keys et al. (1995). In contrast to the outer coastal plain, this region has more rugged terrain and hilly topography (McWilliams 1992, Keys et al. 1995). In addition, the southern boundary approximates the range limits of major potential natural vegetation types of Küchler (1964), oak-hickory-pine to the north, and southern mixed hardwood forests to the south.

Data: http://east.tnc.org/assessment/43/