List of ecoregions in the United States (EPA)

This list of ecoregions in the United States provides an overview of United States ecoregions designated by the U.S. Environmental Protection Agency (EPA) and the Commission for Environmental Cooperation (CEC). The CEC was established in 1994 by the member states of Canada, Mexico, and the United States to address regional environmental concerns under the North American Agreement on Environmental Cooperation (NAAEC), the environmental side accord to the North American Free Trade Agreement (NAFTA). The Commission's 1997 report, "Ecological Regions of North America", provides a framework that may be used by government agencies, non-governmental organizations, and academic researchers as a basis for risk analysis, resource management, and environmental study of the continent's ecosystems.cite web | publisher=Commission for Environmental Cooperation | title=Ecological Regions of North America: Toward a Common Perspective | url=http://www.cec.org/files/PDF/BIODIVERSITY/eco-eng_EN.pdf | date=1997 | accessdate=2008-04-10] In the United States, the EPA and the United States Geological Survey (USGS) are the principal federal agencies working with the CEC to define and map ecoregions. Ecoregions may be identified by similarities in geology, physiography, vegetation, climate, soils, land use, wildlife distributions, and hydrology.

The classification system has four levels, but only Levels I and III are shown on this list. Level I divides North America into 15 broad ecoregions; of these, 12 lay partly or wholly within the United States. Level III subdivides the continent into 182 smaller ecoregions; of these, 104 lay partly or wholly with the United States. [cite web | title=Ecoregion Maps and GIS Resources | publisher=United States Environmental Protection Agency | url=http://www.epa.gov/wed/pages/ecoregions.htm | accessdate=2008-04-10] Level IV is a further subdivision of Level III ecoregions. Level IV mapping is still underway but is complete across most of the United States. For an example of Level IV data, see List of ecoregions in Oregon and the associated articles. The classification system excludes the U.S. state of Hawaii, which is not part of the North American mainland.

Ecoregions in the United States

Marine West Coast Forest

*1 Coast Range
*2 Puget Lowland
*3 Willamette Valley
*111 Ahklun and Kilbuck Mountains
*113 Alaska Peninsula Mountains
*115 Cook Inlet
*119 Pacific Coastal Mountains
*120 Coastal Western Hemlock-Sitka Spruce Forests

Northwestern Forested Mountains

*4 Cascades
*5 Sierra Nevada
*9 Eastern Cascades Slopes and Foothills
*11 Blue Mountains
*15 Northern Rockies
*16 Idaho Batholith
*17 Middle Rockies
*19 Wasatch and Uinta Mountains
*21 Southern Rockies
*41 Canadian Rockies
*77 North Cascades
*78 Klamath Mountains
*105 Interior Highlands
*116 Alaska Range
*117 Copper Plateau
*118 Wrangell Mountains

Mediterranean California

*6 Southern and Central California Chaparral and Oak Woodlands
*7 Central California Valley
*8 Southern California Mountains

North American Deserts

*10 Columbia Plateau
*12 Snake River Plain
*13 Central Basin and Range
*14 Mojave Basin and Range
*18 Wyoming Basin
*20 Colorado Plateaus
*22 Arizona/New Mexico Plateau
*24 Chihuahuan Deserts
*80 Northern Basin and Range
*81 Sonoran Basin and Range

Temperate Sierras

*23 Arizona/New Mexico Mountains

Great Plains

*25 Western High Plains
*26 Southwestern Tablelands
*27 Central Great Plains
*28 Flint Hills
*29 Central Oklahoma/Texas Plains
*30 Edwards Plateau
*31 Southern Texas Plains
*34 Western Gulf Coastal Plain
*40 Central Irregular Plains
*42 Northwestern Glaciated Plains
*43 Northwestern Great Plains
*44 Nebraska Sand Hills
*45 Piedmont
*46 Northern Glaciated Plains
*47 Western Corn Belt Plains
*48 Lake Agassiz Plain

Eastern Temperate Forest

*32 Texas Blackland Prairies
*33 East Central Texas Plains
*35 South Central Plains
*36 Ouachita Mountains
*37 Arkansas Valley
*38 Boston Mountains
*39 Ozark Highlands
*51 North Central Hardwood Forests
*52 Driftless Area
*53 Southeastern Wisconsin Till Plains
*54 Central Corn Belt Plains
*55 Eastern Corn Belt Plains
*56 Southern Michigan/Northern Indiana Drift Plains
*57 Huron/Erie Lake Plains
*59 Northeastern Coastal Zone
*60 Northern Appalachian Plateau and Uplands
*61 Erie Drift Plain
*63 Middle Atlantic Coastal Plain
*64 Northern Piedmont
*65 Southeastern Plains
*66 Blue Ridge
*67 Ridge and Valley
*68 Southwestern Appalachians
*69 Central Appalachians
*70 Western Allegheny Plateau
*71 Interior Plateau
*72 Interior River Valleys and Hills
*73 Mississippi Alluvial Plain
*74 Mississippi Valley Loess Plains
*75 Southern Coastal Plain
*82 Laurentian Plains and Hills
*83 Eastern Great Lakes and Hudson Lowlands
*84 Atlantic Coastal Pine Barrens

Northern Forests

*49 Northern Minnesota Wetlands
*50 Northern Lakes and Forests
*58 Northeastern Highlands
*62 North Central Appalachians

Tropical Wet Forests

*76 Southern Florida Coastal Plain

outhern Semi-Arid Highlands

*79 Madrean Archipelago

Taiga

*101 Arctic Coastal Plain
*102 Arctic Foothills
*103 Brooks Range
*104 Interior Forested Lowlands and Uplands
*106 Interior Bottomlands
*107 Yukon Flats
*108 Ogilvie Mountains

Tundra

*109 Subarctic Coastal Plains
*110 Seward Peninsula
*112 Bristol Bay-Nushagak Lowlands
*114 Aleutian Islands

Listings by state

*List of ecoregions in Oregon

ee also

*Ecoregions defined by the Commission for Environmental Cooperation and partner agencies:
**List of ecoregions in North America (CEC)

*The conservation group World Wildlife Fund maintains an alternate classification system:
**List of ecoregions (WWF)
**List of ecoregions in the United States (WWF)

References