Level I: North America has been divided 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.
Level II: The 50 level II ecological regions that have been delineated are intended to provide a more detailed description of the large ecological areas nested within the level I regions.
Level III: Level III mapping describes smaller ecological areas nested within level II regions. At level III, the continent currently contains 182 ecological regions. These smaller divisions enhance regional environmental monitoring, assessment and reporting, as well as decision-making. Because level III regions are smaller, they allow locally defining characteristics to be identified, and more specifically oriented management strategies to be formulated