The Cascadia bioregion contains 75 distinct ecoregions, and extends for more than 2500 miles from the Copper River in Southern Alaska, to Cape Mendocino in the South, and east as far as the Yellowstone Caldera and continental divide. Cascadian bioregionalism deals with the connected ecological, environmental, economic, and cultural ties that are prevalent throughout the U.S. Pacific Northwest and distance the area from their eastern counterparts. The argument is that those in Washington and Oregon in the United States have much more in common with those in British Columbia, Canada, than those in Washington D.C.
The Cascadia Bioregion is also referred to as the Pacific Northwest Bioregion and encompasses all of the state of Washington, and portions of Oregon, Idaho, California, Nevada, Wyoming, Montana, Alaska, Yukon, and British Columbia. Bioregions are geographically based areas defined by land or soil composition, watershed, climate, flora, and fauna. The Cascadia Bioregion claims the entire watershed of the Columbia River (as far as the Continental Divide), as well as the Cascade Range from Northern California well into Canada. It's also considered to include the associated ocean and seas and their ecosystems out to the continental slope.
The delineation of a bioregion has environmental stewardship as its primary goal, with the belief that political boundaries should match ecological and cultural boundaries. Cascadia Bio Region boundaries. The area from Vancouver, B.C. down to Portland, Oregon has been termed a megaregion by the U.S. and Canadian governments, especially along the 'Cascadian Corridor'. Megaregions are defined as areas where "boundaries begin to blur, creating a new scale of geography now known as the megaregion. These areas have interlocking economic systems, shared natural resources, and ecosystems, and common transportation systems link these population centers together. This area contains 17% of Cascadian land mass, but more than 80% of the Cascadian population. The Canada–US border is diminishing in the face of further economic, political and cultural integration with such programs as the enhanced drivers license program – which can be used to get across the Canada–US border between Washington and British Columbia.