The prairie is a narrow strip across the state from the Mississippi River to the border of Alabama. It is only 40 miles (64 km) across at its widest,  and generally 10–30 miles (16–48 km) wide. It runs in a diagonal line from near Jackson in the northwest, through Bienville National Forest and southeast to the Alabama border. 
The contrast between the alkaline soil of the prairies and the acidic soil of the forests causes the sharp delineation in plant types in each region. In the western portion of the prairie, the soil is a brown loess loam over calcareous clay. In hilly areas, the clay is covered by red and yellow sand from the Pliocene epoch.  The underlying clay, an identifying component of the Jackson Prairie Belt, shrinks and swells dramatically based on the amount of rainwater. Each cycle adds to the mounds and depressions, building them up over time. 
The prairies depend on periodic outbreaks of fire to keep the forest from overgrowing the prairie.
Because of the soil and climate, this ecoregion is ideally suited for farming, leading to most of the prairie being converted into farmland and crop agriculture. There are a few remaining sections in the Bienville National Forest, including the largest remaining undisturbed portion at the Harrell Prairie Botanical Area. 
- Cummins, James L. "Grasslands Reserve Program". Mississippi Fish and Wildlife Foundation. Archived from the original on 2008-05-13. Retrieved 2009-04-05.
- "Harrell Prairie Botanical Area". United States Forest Service. Retrieved 2009-03-31.
- Federal Writers' Project, Federal Writers' Project Mississippi, Mississippi (1959). Mississippi: A Guide to the Magnolia State. US History Publishers. p. 34. ISBN 978-1-60354-023-0.
- Lowe, Ephraim Noble (1921). Plants of Mississippi: A List of Flowering Plants and Ferns. Hedermann Brothers. p. 47.
- McGinnis, Helen (1995). Hiking Mississippi: A Guide to Trails and Natural Areas. University Press of Mississippi. p. 14. ISBN 978-0-87805-664-4. Retrieved 2009-03-30.