Western Great Plains

Despite the promises of boosters, rain did not follow the plow to these open prairie parklands. In fact, evaporation usually exceeds precipitation in these semiarid plains, where drought, wildfire, and grazing help curb the spread of woodlands.  Prairie potholes in the northern plains serve as the continent’s waterfowl factory.  Towards the west, burrowers like prairie dogs, and the black-footed ferrets that prey on them, share the short-grass prairie with North America’s fastest land animal, the pronghorn.

Dry western plains extending from southern Alberta and Saskatchewan south to central Texas.

Climate is dry temperate; reaching extremes of continentality (summer-winter temperature extremes) in the north.  Mean annual temperature of 8.7ºC, (47ºF) with average annual precipitation of 363mm (14 inches).

Rolling to flat landscapes, varying from glacial till plains in the extreme north, to ancient alluvial plains in the south.  Vast sandhills and loess hills subsequently eroded, formed from Pleistocene outwash of the Rocky Mountains, then wind-blown across the plains. Shortgrass prairie dominates the southwestern quarter of the Division, transitioning in the south to semi-desert grassland and desert scrub in the Chihuahuan Desert. 

Also in south-central Texas, the Edwards Plateau, including extensive hill country of limestone and shallow soils.  North of Colorado, extending through southern Alberta and Saskatchewan, a mixed grass prairie transitions to fescue grassland and aspen parkland.  To the east, a long north-south belt of mixed grass prairie forms the eastern transition to deep, black-soil Tallgrass prairie of the Eastern Great Plains Division. Prairie wildfire was characteristic, covering enormous areas each year with fast-moving fires.

History and Trends
Vast Bison herds sustained Native Americans and other biota alike. Post Civil War development of the western plains centered on grazing and irrigated agriculture. Cities are few (e.g., Denver, Lincoln, Omaha), but important economic centers. Energy development (coal, natural gas, oil, wind) continue and may expand in certain areas.

Western Great Plains Ecoregions

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