Ecological regions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. These general purpose regions are critical for structuring and implementing ecosystem management strategies across international, national, province and state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas.A Roman numeral hierarchical scheme has been adopted for different levels for ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 50 regions. At Level III, there are currently 181 ecological regions for North America.These files of Level I ecological regions of North America are a 2010 update and revision of files developed by Canada, the United States, and Mexico in 2006, which were an update of earlier files from the late 1990’s in a cooperative project for the Commission for Environmental Cooperation (CEC 1997). The CEC was created under the North American Agreement on Environmental Cooperation (NAAEC) to address regional environmental concerns, help prevent potential trade and environmental conflicts and promote the effective enforcement of environmental law. The Agreement complements the environmental provisions established in the North American Free Trade Agreement (NAFTA).The 2006 version of North American ecological regions was developed in a meeting between representatives of the three nations in April 2006 in Newport, Oregon. This 2010 version updates mainly the United States ecoregions in those states where new ecoregion mapping has occurred since 2006, particularly in Michigan, New York, and New England. Issues relating to topology (overlaps and gaps in the data) and to waterbodies were the only revisions for Canada and Mexico. Many small waterbodies in Mexico and in coastal areas of the United States were merged with surrounding ecoregions to conform with their depiction in the interior United States and Canada. The 2010 files are considered draft and subject to further refinements.Commission for Environmental Cooperation. 1997. Ecological regions of North America: toward a common perspective. Commission for Environmental Cooperation, Montreal, Quebec, Canada. 71pp.U.S. Environmental Protection Agency, 2010, Level III ecoregions of the continental United States (revision of Omernik, 1987): Corvallis, Oregon, USEPA National Health and Environmental Effects Research Laboratory, Map M-1, various scales.Comments and questions regarding the North America Ecoregions should be addressed to Glenn Griffith, Dynamac Corporation, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:griffith.glenn@epa.gov. Alternate: James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:omernik.james@epa.gov
