The Great Plains: Vast Flatlands Between the Rockies & Mississippi

The enormous expanse of flat to gently rolling land between the Rocky Mountains (west) and the Mississippi River (east) is the Great Plains.

Scope & Scale

• Area: ~2.8M km² (1.1M mi²) — ~1/3 of contiguous U.S.
• North–South: Canadian Prairie Provinces (AB, SK, MB) → Texas / Rio Grande.
• East–West: ~500–800 km (300–500 mi) wide.
• Elevation: ~600 m (2,000 ft) at eastern edge → ~1,500 m (5,000 ft) at Rockies' foot.

Defining Features

• Grasslands: Tallgrass (east), mixed-grass (central), shortgrass (west). Now largely converted to cropland (corn, wheat, soy, sorghum).
• Rivers: Missouri, Platte, Arkansas, Red, Canadian, Pecos — eastward flowing, life lines.
• Climate: Continental—hot summers, cold winters, low/modest rain (250–750 mm / 10–30 in), high evaporation, frequent drought, severe storms (tornado alley).
• Geology: Thick sedimentary cover (Mesozoic/Cenozoic) over Precambrian basement. Ogallala Aquifer (High Plains Aquifer) — critical irrigation source, now declining.

Ecological & Cultural Significance

• Historic bison range (30–60M); now restored in patches.
• Prairie dog towns, pronghorn, swift fox, burrowing owl, grassland birds (declining).
• Indigenous nations: Lakota, Cheyenne, Comanche, Kiowa, Blackfeet, Crow, Pawnee, etc.
• Homestead Act, Dust Bowl, grain belt, cattle culture, energy (oil, gas, wind).

The Great Plains is not "empty"—it's a vast, dynamic, semi-arid grassland biome shaped by wind, fire, grazing, and water. One of North America's defining landscapes.