Ecological Subregions: Sections and Subsections for the conterminous United States
This map and accompanying descriptions were developed through participation with numerous individuals from federal and state agencies and non-governmental organizations using criteria defined in the National Hierarchical Framework of Ecological Units. Delineation generally involved the “top-down approach” of subdividing section level units. A “bottom-up approach” was used where landscape level units had been developed. Additional information is available on the process used for delineation of map units. Subsection maps were compiled at scales of 1:500,000 and 1:1,000,000, recompiled and joined at a scale of 1:1,000,000 and presented at a scale of 1:3,500,000.