List of ecoregions in the United States (EPA)

This list of ecoregions in the United States provides an overview of United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

ecoregions designated by the U.S. Environmental Protection Agency

United States Environmental Protection Agency

The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...

(EPA) and the Commission for Environmental Cooperation

Commission for Environmental Cooperation

The Commission for Environmental Cooperation was established by Canada, Mexico, and the United States to implement the North American Agreement on Environmental Cooperation , the environmental side accord to the North American Free Trade Agreement...

(CEC). The CEC was established in 1994 by the member states of Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, and the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

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

North American Free Trade Agreement

The North American Free Trade Agreement or NAFTA is an agreement signed by the governments of Canada, Mexico, and the United States, creating a trilateral trade bloc in North America. The agreement came into force on January 1, 1994. It superseded the Canada – United States Free Trade Agreement...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 organization

Non-governmental organization

A non-governmental organization is a legally constituted organization created by natural or legal persons that operates independently from any government. The term originated from the United Nations , and is normally used to refer to organizations that do not form part of the government and are...

s, and academic researchers as a basis for risk analysis

Risk management

Risk management is the identification, assessment, and prioritization of risks followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events or to maximize the realization of opportunities...

, resource management

Natural resource management

Natural resource management refers to the management of natural resources such as land, water, soil, plants and animals, with a particular focus on how management affects the quality of life for both present and future generations ....

, and environmental study

Environmental science

Environmental science is an interdisciplinary academic field that integrates physical and biological sciences, to the study of the environment, and the solution of environmental problems...

of the continent's ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s. In the United States, the EPA and the United States Geological Survey

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

(USGS) are the principal federal agencies working with the CEC to define and map ecoregions. Ecoregions may be identified by similarities in geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, physiography, vegetation

Vegetation

Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...

, climate

Climate

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

, soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

s, land use

Land use

Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...

, wildlife

Wildlife

Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....

distributions, and hydrology

Hydrology

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

.

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. 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

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

of Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, which is not part of the North American mainland.

Ecoregions in the United States

Marine West Coast Forest

1 Coast Range
Coast Range (ecoregion)
The Coast Range ecoregion is a Level III ecoregion designated by the Environmental Protection Agency in the U.S. states of Washington, Oregon, and California...
2 Puget Lowland
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
3 Willamette Valley
Willamette Valley (ecoregion)
The Willamette Valley ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon and Washington. Slightly larger than the Willamette Valley for which it is named, the ecoregion contains fluvial terraces and floodplains of the...
111 Ahklun Mountains
Ahklun Mountains
The Ahklun Mountains are located in the northeast section of the Togiak National Wildlife Refuge in southwest Alaska. They extend southwest from the Kanektok and Narogurum Rivers to Hagemeister Strait and Kuskokwim Bay and support the only existing glaciers in western Alaska...

and Kilbuck Mountains
113 Alaska Peninsula Mountains
115 Cook Inlet
Cook Inlet
Cook Inlet stretches from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage....
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

4 Cascades
Cascades (ecoregion)
The Cascades ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Washington, Oregon, and California...
5 Sierra Nevada
9 Eastern Cascades Slopes and Foothills
11 Blue Mountains
Blue Mountains (ecoregion)
The Blue Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. state of Oregon, with small areas over the state border in Idaho and southeastern Washington...
15 Northern Rockies
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
16 Idaho Batholith
17 Middle Rockies
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
19 Wasatch and Uinta Mountains
21 Southern Rockies
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
41 Canadian Rockies
Canadian Rockies
The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. They are the eastern part of the Canadian Cordillera, extending from the Interior Plains of Alberta to the Rocky Mountain Trench of British Columbia. The southern end borders Idaho and Montana of the USA...
77 North Cascades
78 Klamath Mountains
Klamath Mountains (ecoregion)
The Klamath Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon and California. It lies inland of the Coast Range ecoregion, extending from the Umpqua Valley in the north to the Sacramento Valley in the south...
105 Interior Highlands
116 Alaska Range
Alaska Range
The Alaska Range is a relatively narrow, 650-km-long mountain range in the southcentral region of the U.S. state of Alaska, from Lake Clark at its southwest end to the White River in Canada's Yukon Territory in the southeast...
117 Copper Plateau
Copper Plateau taiga
The Copper Plateau taiga is an ecoregion of North America, as defined by the World Wildlife Fund categorization system and the Commission for Environmental Cooperation, in the Taiga and Boreal forests, Biome, Alaska.-Setting:...
118 Wrangell Mountains
Wrangell Mountains
The Wrangell Mountains are a high mountain range of eastern Alaska in the United States. Much of the range is included in Wrangell-Saint Elias National Park and Preserve. The Wrangell Mountains are almost entirely volcanic in origin, and they include the second and third highest volcanoes in the...

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

Mediterranean California

6 Southern and Central California Chaparral and Oak Woodlands
California chaparral and woodlands
The California chaparral and woodlands is a terrestrial ecoregion of lower northern, central, and southern California and northwestern Baja California , located on the west coast of North America...
7 Central California Valley
8 Southern California Mountains
Peninsular Ranges
The Peninsular Ranges are a group of mountain ranges, in the Pacific Coast Ranges, which stretch from southern California in the United States to the southern tip of Mexico's Baja California peninsula; they are part of the North American Coast Ranges that run along the Pacific coast from Alaska...

North American Deserts

10 Columbia Plateau
Columbia Plateau (ecoregion)
The Columbia Plateau ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon and Washington, with small areas over the Washington state border in Idaho...
12 Snake River Plain
Snake River Plain (ecoregion)
The Snake River Plain ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Idaho and Oregon. It follows the Snake River across Idaho, stretching roughly from the Wyoming border to Eastern Oregon in the xeric intermontane west...
13 Central Basin and Range
Central Basin and Range ecoregion
The Central Basin and Range ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency with 26 different Level IV ecoregions...
14 Mojave Basin and Range
18 Wyoming Basin
Wyoming Basin
The Wyoming Basin physiographic province is a geographic area through which the Continental Divide of the Americas traverses. The province includes the Washakie and Great Divide Basins, and is demarcated by the following:*southwest: Uinta Mountains...
20 Colorado Plateaus
22 Arizona/New Mexico Plateau
24 Chihuahuan Deserts
Chihuahuan Desert
The Chihuahuan Desert is a desert, and an ecoregion designation, that straddles the U.S.-Mexico border in the central and northern portions of the Mexican Plateau, bordered on the west by the extensive Sierra Madre Occidental range, and overlaying northern portions of the east range, the Sierra...
80 Northern Basin and Range
Northern Basin and Range (ecoregion)
The Northern Basin and Range ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon, Idaho, Nevada, Utah, and California. It contains dissected lava plains, rolling hills, alluvial fans, valleys, and scattered mountain ranges...
81 Sonoran Basin and Range
Sonoran Desert
The Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...

Great Plains

25 Western High Plains
High Plains (United States)
The High Plains are a subregion of the Great Plains mostly in the Western United States, but also partly in the Midwest states of Nebraska, Kansas, and South Dakota, generally encompassing the western part of the Great Plains before the region reaches the Rocky Mountains...
26 Southwestern Tablelands
27 Central Great Plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
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
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
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

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