Alabama Landscapes

The Gulf Coastal Plain

Table of Contents

UPCoastal PlainPiedmontValley and RidgeHighland RimCumberland Plateau

UPCoastal Plain  GeologyCP RiversCP Soils and VegetationCP Phys Districts




The East Gulf Coastal Plain (hereafter called the Coastal Plain) is the largest physiographic section in the state, occupying about 60% of Alabama.  Its northern boundary is called the Fall Line and is a large sweeping curve from Phenix City (Lee County) through Centerville (Shelby County), Tuscaloosa (Tuscaloosa County) and the Alabama/Mississippi border west of Florence (Lauderdale County).  It is bordered successively from southeast to northwest by the Piedmont, Valley and Ridge, Cumberland Plateau and Highland Rim sections (Figure CP1).  The Coastal Plain continues northwest  into Mississippi, where it occupies most of the state, and northeast into Georgia.

Figure  CP1.  Location Map of The East Gulf Coastal Plain.  Note: small outliers of East Gulf Coast Plain in Lauderdale and Colbert Counties not shown. (Base map from Cartographic Research Lab,  University of Alabama)

In 2000, the Coastal Plain contained about 1.9 million people, almost 500,000 of whom lived in Montgomery the State Capital), Mobile and Tuscaloosa.   Population density was low (~63 persons/square mile) and the three sparsest population counties in the state (Greene, Bullock, and Perry) contained fewer than 12,000 people.  Thirty two percent of the population was Black or African American, and Blacks or African Americans are the majority of the population in 9 counties.

 Four major highways run through the Coastal Plain with Montgomery as the hub. I-65, which connects Montgomery to Mobile; and H-231, which connects Montgomery to Dothan run roughly north-south, while I-85 connects Montgomery to Atlanta, and H80 connects Montgomery westward to the towns of the Black Prairie.

 In general climate is warmer and wetter from the Fall Line to the coast.  Average annual temperature and rainfall increase from 65oF and 54 inches in Montgomery (Montgomery County) to 68oF and 65 inches in Mobile (Mobile County)  Higher summer rainfall in Mobile and warmer winter temperatures show the modifying effect of the Gulf Coast on climate.

An abbreviated version of this article occurs in the Encyclopedia of Alabama (



UPCoastal PlainPiedmontValley and RidgeHighland RimCumberland Plateau

UPCoastal Plain  GeologyCP Soils and VegetationCP Phys DistrictsCP Rivers