Research overview: I-90 Snoqualmie Pass wildlife crossings

Interstate 90 over Snoqualmie Pass in Washington State bisects forested habitat in the Cascade Range, and an extensive program of wildlife overpasses and underpasses has been built to restore movement across it. This overview synthesizes how monitoring, using cameras, track plates, and telemetry, has documented use of these structures by a range of species, and the role of connectivity in allowing carnivores and their prey to move between habitat blocks separated by one of the region's busiest highways. The overview discusses the design of vegetated overpasses, accompanying fencing that funnels animals to crossings, and the long-term data needed to judge effectiveness. The Snoqualmie Pass project is a major North American example of integrating crossing structures into highway reconstruction to reconnect landscapes for wildlife movement.