The North Cascades Ecosystem (NCE) comprises an area of 24,800 km2 in Washington, with an additional 10,350 km2 extending north into British Columbia. In the US, 90% of the NCE is managed by the US Forest Service, the US National Park Service, and the State of Washington, and approximately 41% falls within Forest Service wilderness or the North Cascades National Park Service Complex.
I-90 intersects the Cascades at Snoqualmie Pass, where growing traffic volume currently averages 27,000 vehicles per day. This area has been recognized as a critical link in the north-south movement of wildlife in the Cascades. The Washington Department of Transportation (WSDOT) recently began to improve 15 miles of I-90 near Snoqualmie Pass, with one of its goals being to enhance ecological connectivity via wildlife crossing structures and fencing.
Meanwhile, Route 2 is a two-lane highway where it crosses the Cascades, with an average traffic volume of 3,800 vehicles per day. Ski area development, power-line corridors, and residential development also potentially affect carnivore movement in the Route 2 corridor.
Lastly, Highway 20 comprises two lanes where it bisects North Cascades National Park in northernmost Washington, with an average traffic volume of 4,800 vehicles per day during non-winter (a major section of this road is closed to automobile traffic during the winter)