The Great Plains: Vast Flatlands Between the Rockies and Mississippi

The Great Plains is the expansive, relatively flat region stretching from the Rocky Mountains' eastern front to the Mississippi River (and the Central Lowland). It spans ~3,000 km N–S (Canada to Mexico) and 500–800 km E–W.

Geography

• Underlain by horizontal sedimentary strata (Mesozoic/Cenozoic).
• Gentle eastward slope (~1,500 m to ~300 m).
• Subregions: High Plains (west), Dissected Till Plains (northeast), Llano Estacado (south).

Ecology & Economy

• Native: mixed/shortgrass prairie; bison, pronghorn, prairie dogs.
• Converted: world's breadbasket—wheat, corn, sorghum, cattle.
• Ogallala Aquifer: critical irrigation source; depleting.

Climate

Continental: hot summers, cold winters, low precipitation (250–750 mm west–east), high variability, violent storms (tornado alley).

Significance

The Plains are a continental-scale ecotone and agricultural engine. Their "flatness" is deceptive—subtle relief guides water, wind, and life.