Innovative Colorado Wildlife Overpass Reduced Collisions With Animals by 91%
In Colorado, a moose safely crosses a busy highway by using one of the state's wildlife overpasses.
Photo provided by Colorado Parks and Wildlife
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Read more storiesColorado has dramatically reduced wildlife collisions and reconnected habitats divided by one of its busiest highways.
Since opening in December 2025, the Greenland Wildlife Overpass in Douglas County, Colorado, has given elk, bears and other animals a safer route across Interstate 25. The $15 million project, developed through a partnership of transportation officials, wildlife agencies and conservation groups, is North America’s largest wildlife overpass. Wildlife-vehicle crashes along the stretch have reportedly dropped by 91% since the crossing opened.
Measuring 209 feet long and 200 feet wide, the bridge spans six lanes of traffic south of Castle Rock and reconnects roughly 39,000 acres of habitat. Soil and vegetation cover its surface, creating a land bridge across a highway that has restricted wildlife movement for decades.
Its open design provides a route for elk and pronghorn, which often avoid enclosed underpasses. Cameras have recorded both species using the bridge, along with bears and other wildlife.
A safer crossing for Colorado’s wildlife
The Greenland Wildlife Overpass reconnects wildlife habitat across Interstate 25 in Douglas County, Colorado.
Watch on Facebook ↗Why this news matters for all of us
Each year, nearly 2 million large animals are killed on U.S. highways. Highways have long created significant fragmentation, public safety hazards, and even genetic isolation among wildlife species affected by the stark division of the busy, massive roads.
Notes Brandon Marette, Colorado Parks and Wildlife biologist, I-25 was effectively a deadly wall animals were forced to navigate to reach what is essentially the 'other side' of their own home.
Moreover, over 25 years of National Park Service research has found the harms of habitat fragmentation to be significant, even including genetic effects in mountain lions separated from one another over long periods of time, highlighting the importance of connectivity and the wider construction of wildlife crossings.
Similar research conducted at Interstates 15 and Highway 101 in California have similarly found that highways serve not merely as hazards, but significant barriers with impacts down to the genetic level in local wildlife populations.
More recent reports have even found that the fragmentation caused by highways can even cause certain wildlife populations to become unsustainable altogether, promoting species die-off.
The overpass is a key example of the type of infrastructure that creates significant benefits for both human and wildlife populations. It's success demonstrates that with little investment, significant safety gains on highways are easily attainable while simultaneously respecting and protecting the environments and biodiversity necessary for our continued survival as a species.
The reduction in car collisions also alleviates the burden placed on highway patrol services while safeguarding drivers who are liable to lose their car entirely in the case of a severe collision with a larger species.
And I mean, lastly, who doesn't want to see less roadkill during their commute? Who doesn't want to know that the very highway system they resent as it shuffles them to whatever they have to do for a living is at least not also cutting local wildlife populations in two? Who doesn't want to see a green overpass?
Take Action
Help make wildlife crossings a standard part of road planning.
2026 is a big year for the future of wildlife crossings such as these overpasses. House and Senate members on Transportation and Infrastructure or Environment and Public Works committees are the most strategic targets to encourage the inclusion of Wildlife Overpasses and similar projects on future bills.
Start locally
Put a crossing on the map.
State transportation and wildlife agencies help decide where crossings get built. Organize around a specific road, a clear request and a group willing to keep showing up.
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Find the people who plan your roads
Contact your state transportation department, wildlife agency and regional planning body. Ask who handles wildlife crossings and habitat connectivity.
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Make your case with local data
Request wildlife collision records and habitat studies. Use them to map collision hotspots and identify where a crossing could help.
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Ask officials to take a specific step
Ask county commissioners, city councils and state lawmakers to support a crossing study, adopt a resolution or add a project to transportation plans.
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Show up and follow up
Attend public hearings and planning meetings. Submit written comments, track deadlines and keep asking officials for updates.
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Push for state and local funding
Ask lawmakers to budget for planning, grant matching funds and maintenance so promising projects can move forward.
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Protect the land on both sides
Bring in willing landowners and land trusts to explore conservation easements and keep habitat connected to proposed crossings.
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Build a coalition that lasts
Welcome neighbors, conservationists, farmers, Tribal nations and road safety advocates around shared goals. Plan for sustained involvement.
Protect federal funding
Advocate for keeping wildlife crossings in the next transportation bill.
The Wildlife Crossings Pilot Program’s original authorization covered fiscal years 2022 through 2026. Ask Congress to renew and expand dedicated funding for safe crossings and connected habitats.
Use Environment America’s action form to contact your U.S. House representative.
Send your representative a messageUnderstand the process
The committees shaping the bill.
The House Transportation and Infrastructure Committee and Senate Environment and Public Works Committee help shape surface transportation legislation. Use the membership lists to see whether your lawmakers serve on either committee.
Support the work
Wildlife Crossing Fund
Sign up for updates or donate to support an organization dedicated entirely to using wildlife crossings to boost animal conservation, create green infrastructure and improve climate change resilience.
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