Washington has reached a striking milestone in its effort to make a major highway safer for wildlife. More than 10,000 successful animal crossings have now been recorded at the I-90 wildlife overcrossing near Snoqualmie Pass. The milestone was reached in July 2026 and was announced by the Washington State Department of Transportation. The bridge is part of a wider network of wildlife crossings built along the interstate to reconnect habitats divided by the highway. Since monitoring began in 2014, nearly 40,000 wildlife crossings have been recorded across the overcrossing and 11 undercrossings in the Snoqualmie Pass corridor. The structures give animals a way to move between habitats without entering traffic. They also help reduce the risk of collisions that can kill wildlife and injure motorists.
Washington bridge designed for wildlife
The I-90 wildlife overcrossing sits in the Cascade Mountains near Snoqualmie Pass. It allows animals to pass over the interstate instead of attempting to cross the road itself. Vegetation and natural materials are used to make the structure resemble the surrounding landscape. Wildlife fencing guides animals towards the crossings and helps prevent them from reaching the highway. The overcrossing is part of the larger Snoqualmie Pass East project, which combines highway improvements with measures to reconnect wildlife habitat. The corridor is an important route through the Cascades and carries more than 25,000 vehicles a day. That volume makes crossing the interstate dangerous for many species.
More than 10,000 crossings on one overpass
WSDOT said its cameras recorded the 10,000th successful crossing on the I-90 wildlife overcrossing in July 2026. The figure applies to the overcrossing itself. It is separate from the wider total recorded across the network of crossings in the area. Nearly 40,000 wildlife crossings have been documented since 2014 across the overcrossing and 11 undercrossings. Motion-triggered cameras have recorded animals including deer, elk and coyotes using the structures. Other monitoring has documented smaller species as well. These include western toads, coastal giant salamanders and American pika. Bull trout have also been documented using pools beneath the Gold Creek Bridge.
The crossings reconnect a fragmented habitat
The project is about more than preventing road deaths. Interstate highways can divide animal populations and restrict their access to food, water and seasonal habitats. WSDOT says safe crossings allow wildlife to regain access to parts of their natural range. This can also help reduce the isolation of animal populations. That matters because isolated populations can face reduced genetic diversity over time. The Snoqualmie Pass corridor connects habitat on both sides of I-90. The crossings allow animals to move through this landscape without having to negotiate heavy traffic. The Washington Department of Fish and Wildlife identifies habitat connectivity as an important conservation need in the state and lists the Snoqualmie area among locations where wildlife movement and road safety are closely linked.
Wildlife collisions have a heavy cost
The crossings also address a major road safety problem. WSDOT has reported that wildlife-vehicle collisions in completed sections of the Snoqualmie Pass East project have fallen to consistently low or non-existent levels. The agency reported that 39,258 wildlife carcasses were removed from Washington state highways between 2019 and 2023. In the sections of I-90 where the wildlife crossings and fencing are in place, the number of carcasses has fallen dramatically. Wildlife collisions also create significant costs for drivers and public agencies. WSDOT estimates the average economic cost of a deer collision at about $14,014. An elk collision costs about $45,445 on average. A moose collision is estimated at about $82,646. These calculations include factors such as vehicle damage, injuries and fatalities.
The project is still expanding
The 10,000th crossing is not the end of Washington’s effort. The Snoqualmie Pass East project is still under construction. WSDOT plans to add more wildlife crossings as work continues along I-90. The agency has said it plans to build 15 additional undercrossings and another overcrossing along the Snoqualmie Pass East corridor by 2031. The wider project is scheduled to continue into the early 2030s. The approach combines wildlife crossings with fencing and habitat connectivity measures. This is important because a bridge or tunnel alone cannot ensure that animals reach it safely. Fencing helps guide wildlife towards the structures and keeps them away from traffic.
A model for wildlife-friendly roads
Washington’s experience reflects a wider shift in how roads are designed in wildlife habitat. Research has found that properly designed crossings can reduce wildlife-vehicle collisions while allowing animals to maintain movement across fragmented landscapes. A peer-reviewed study that examined wildlife crossing structures in Washington found that they were associated with fewer wildlife-vehicle collisions. The researchers found an average reduction of one to three collisions per mile each year depending on the type and location of the structure.The Snoqualmie Pass milestone offers a clear example of how such infrastructure can serve both wildlife and people. More than 10,000 animals have now been recorded using one overcrossing without entering the highway. Nearly 40,000 crossings have been recorded across the wider network since 2014. With more structures planned, Washington is continuing to turn a section of one of its busiest mountain highways into a safer passage for animals moving through the Cascades.
