Since 2014, Washington State’s Snoqualmie Pass wildlife overpass has recorded over 10,000 successful animal crossings, drastically cutting collisions and serving as a model for combining transportation infrastructure with conservation efforts.
- 10,000 animal crossings recorded with no roadkill
- Over 39,000 carcasses removed statewide vs. near zero on I-90 stretch
- Plans for more crossings to enhance wildlife connectivity by 2031
What happened
Twelve years ago, the Washington State Department of Transportation (WSDOT) opened a wildlife overpass at Snoqualmie Pass on Interstate 90 to provide a safe corridor for animals crossing the busy highway. Since then, trail cameras have documented over 10,000 successful crossings on the overpass alone, with nearly 40,000 crossings recorded on the entire Snoqualmie Pass area including 11 undercrossings. This milestone highlights the overpass’s role in preventing collisions and fostering wildlife movement across the Cascade Mountains.
Statewide, there have been more than 39,000 wildlife carcasses removed from highways between 2019 and 2023, but in the I-90 Snoqualmie Pass area where the crossing structures exist, roadkill has dropped to almost zero. This demonstrates the dramatic impact the crossing has had in protecting animals and reducing accidents.
Why it feels good
The success of the I-90 Snoqualmie Pass crossing is more than just about wildlife safety; it represents a powerful collaboration between transportation and conservation. These structures help reconnect fragmented habitats, allowing animal populations to maintain healthy genetic diversity and safely access their full range across the landscape. This restoration of ecological integrity is vital for both herds and solitary species moving through one of Washington’s primary wildlife corridors.
Additionally, there are significant economic benefits from reducing wildlife-vehicle collisions. For example, avoiding a single deer collision saves an average of $15,000 while elk collisions can cost $54,000. With large mammal collisions reduced by up to 97% at wildlife crossings nationally, investing in these structures saves the state money while also protecting people and animals.
What to enjoy or watch next
Inspired by this success, WSDOT plans to expand efforts with an additional 15 undercrossings and one more overpass along Snoqualmie Pass East by 2031. These initiatives aim to further enhance safe wildlife movement and connectivity between critical habitats across the Cascade Mountains and the Olympic Peninsula, continuing to forge a future where highways and nature coexist harmoniously.
Conservation Northwest, a key advocate behind the original crossing, continues to push for broader habitat restoration and improved wildlife outcomes along the I-90 corridor. This makes Washington’s approach a national example of how infrastructure projects can boost both ecological health and public safety, setting a hopeful precedent for other regions to follow.