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West-Central Semi-Arid Prairies

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NameColor on MapCEC Code‡
Northwestern Glaciated Plains9.3.1
Northwestern Great Plains9.3.3
Nebraska Sand Hills9.3.4

† Status: ✓ = Complete ○ = Needs Image … = Incomplete ∅ = Stub Only

This code refers to the CEC's Level 3 ecoregion codes for North America, see here.


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About the West-Central Semi-Arid Prairies

The West-Central Semi-Arid Prairies are a large region in the northwestern part of the Great Plains. It extends roughly northwest-southeast, and occupies most of Montana, the western portion of the Dakotas, northeastern Wyoming, and much of northern Nebraska.

The topography is fairly diverse, ranging from flat to tablelands and badlands, with some sand dunes. The climate is a semi-arid continental climate. There is significant seasonality of precipitation, with the wet season usually being May-July. Locally-originating streams are mostly seasonal or intermittent, but there are also perennial streams originating uphill in the Western Cordillera. Seasons are well-defined, with hot summers and cold winters. As one moves west, rainfall decreases, but the coldest winter temperatures are also reduced slightly due to increased distance from the cold air masses that often penetrate furthest close to the center of the continent.

This area was historically covered by short- and mixed-grass prairie. Nowadays there is significant agriculture in the region, although less than the more fertile lands to the east. Use of land for grazing animals is more common than for cropland. Agricultural use of the grasslands in this region is expected to increase.

Most of this region is sparsely populated, and it does not contain any large cities.

In Wyoming, to the southwest, this regions transitions gradually into the Cold Deserts. To the west, and also at a few isolated regions of higher altitude, this region borders the Western Cordillera. Most of this region, however, is surrounded by more of the Great Plains. To the north and east, it transitions to the slightly moister Temperate Prairies, and to the south, the South-Central Semi-Arid Prairies.