List of ecoregions in the United States (EPA)

For an alternate classification system, see List of ecoregions in the United States (WWF).

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.^[1] 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.^[1]^[2] 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.

1 Ecoregions in the United States
2 Listings by state
3 See also
4 References

Ecoregions in the United States

Marine West Coast Forest

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

The corresponding CEC ecoregion in Canada is called the Pacific Maritime Ecozone.

Northwestern Forested Mountains

The corresponding CEC ecoregion in Canada is called the Montane Cordillera Ecozone.

Mediterranean California

North American Deserts

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
46 Northern Glaciated Plains
47 Western Corn Belt Plains
48 Lake Agassiz Plain

The corresponding name in Canada for the same ecoregion is the Prairies Ecozone.

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
45 Piedmont
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
58 Northeastern Highlands
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

The corresponding ecoregion in Canada is named the Mixedwood Plains Ecozone.

Northern Forests

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

The corresponding name in Canada for the same ecoregions are the Boreal Shield and the Atlantic Maritime Ecozones.

Tropical Wet Forests

76 Southern Florida Coastal Plain

Southern 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

References

^ ^a ^b "Ecological Regions of North America: Toward a Common Perspective". Commission for Environmental Cooperation. 1997. http://www.cec.org/files/PDF/BIODIVERSITY/eco-eng_EN.pdf. Retrieved 2008-04-10.
^ "Ecoregion Maps and GIS Resources". United States Environmental Protection Agency. http://www.epa.gov/wed/pages/ecoregions.htm. Retrieved 2008-04-10.

Level III 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

Southern 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

as defined by the United States Environmental Protection Agency [1]