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Ecoregions of North America

Ecoregions are areas where ecosystems (and the type, quality, and quantity of environmental resources) are generally similar. This ecoregion framework is derived from Omernik (1987) and from mapping done in collaboration with EPA regional offices, other Federal agencies, state resource management agencies, and neighboring North American countries. Designed to serve as a spatial framework for the research, assessment, and monitoring of ecosystems and ecosystem components, ecoregions denote areas of similarity in the mosaic of biotic, abiotic, terrestrial, and aquatic ecosystem components with humans being considered as part of the biota. These regions are critical for structuring and implementing ecosystem management strategies across Federal agencies, state agencies, and nongovernmental organizations that are responsible for different types of resources within the same geographic areas.

Ecoregions are identified by analyzing the patterns and composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity. These phenomena include geology, landforms, soils, vegetation, climate, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. A Roman numeral classification scheme has been adopted for different hierarchical levels of ecoregions, ranging from general regions to more detailed.

North America has been divided into:

  • 15 broad, level I ecological regions;
  • 50 level II ecological regions intended to provide a more detailed description of the large ecological areas nested within the level I regions; and
  • 182 Level III ecoregions, which are smaller ecological areas nested within level II regions.

Select a section for additional details about each level, or a list of links to downloadable maps and GIS data files.

FieldValue
Modified
2019-08-05
Release Date
2018-04-13
Identifier
f8c728de-d3ad-4295-b5dc-da28adde20f4
Publisher
Environmental Protection Agency
License
Contact Name
Ferster, Aaron
Contact Email
Public Access Level
Public