This article is part of the Ecoregions Collection

This article presents an overview of the ecoregion classification system for North America that was developed by the Commission for Environmental Cooperation Working Group (CEC) in 1997. The mapping presented here is built upon earlier efforts that had begun individually in all the United States, Mexico, and Canada.  Developing and refining a framework for the study of North American ecological regions was the product of research and consultation between federal, state, provincial and territorial agencies. The Canadian Council on Ecological Areas (CCEA) was the initial group that led and coordinated the development of a North American ecosystem framework in response to initiatives of the Trilateral Committee on Environmental Information. The latter was established by the governments of Canada, Mexico and the United States to foster ways of applying an ecological approach to common North American environmental concerns. Its work was guided by existing national efforts to characterize and report on the sustainability of ecosystems.  A more detailed discussion of the project is presented here.

Level I Ecoregions

Ecosystem provinces of the United States. Source: Commission for Environmental Cooperation Working Group

North America has been broken down into 15 broad, level I ecological regions. These highlight major ecological areas and provide the broad backdrop to the ecological mosaic of the continent, putting it in context at global or intercontinental scales:

• Arctic Cordillera
• Tundra
• Taiga
• Hudson Plains
• Northern Forests
• Northwestern Forested Mountains
• Marine West Coast Forests
• Eastern Temperate Forests
• Great Plains
• North American Deserts
• Mediterranean California
• Southern Semi-Arid Highlands
• Temperate Sierras
• Tropical Dry Forests
• Tropical Humid Forests

Level II Ecoregions

Fifty-two level II ecological regions are delineated that provide a more detailed description of the large ecological areas nested within the Level I regions. For example, the Tropical Humid Forests of level I is the region covering coastal portions of the United States and Mexico, and is composed of six level II regions. Level II ecological regions are useful for national and subcontinental overviews of physiography, wildlife, and land use.

A detailed classification and description of the Level II ecoregions is available here.

See also:

• Level III ecoregions of the United States
• Level IV ecoregions of the United States

Further reading

• Commission for Environmental Cooperation, Ecological Regions of North America--Toward a Common Perspective, (Quebec, Canada, 1997), ISBN 2-922305-18-X
• United States Environmental Protection Agency, Western Ecology Division, Ecoregion Maps and GIS Resources, Accessed 1 May 2009.