Colorado's Massive Wildlife Overpass Has Reduced Animal Collisions by 91%

September 21, 2026

For decades, Interstate 25 in Colorado stood in the way of wildlife trying to reach the other side. Now, a massive wildlife bridge is giving animals a safe way across, and the results have been nothing short of remarkable.

Since opening in December, North America's largest wildlife overpass has helped reduce animal-vehicle collisions in the area by 91%.

Located near the Greenland exit between Larkspur and Monument, the 209-by-200-foot bridge was built to help animals safely navigate a stretch of highway that had become a dangerous barrier to their natural movements.

Before the crossing was built, wildlife collisions were a regular occurrence, with about one deer being hit each day during peak migration periods in the spring and fall.

Today, the scene looks very different.

"Based on the video feed that we're collecting, huge success," said Chuck Attardo, an environmental manager with the Colorado Department of Transportation. "We're seeing elk herds cross the bridge. We're seeing pronghorn for the first time in decades cross over to the west side of I-25 because of the bridge."

And the overpass isn't just for the larger animals.

Bears, deer, coyotes, and other wildlife have also used the crossings. Biologists even arranged logs along part of the bridge to create shelter for smaller animals, helping protect them from predators as they make their way across.

The area is home to the federally threatened Preble's meadow jumping mouse, as well as northern leopard frogs and other small reptiles, amphibians, and rodents that need safe passage, too.

"It's not just the big game species, but also the smaller," Brandon Marette, a wildlife biologist with Colorado Parks and Wildlife, explained.

The project included the enormous overpass, five wildlife underpasses, and fencing designed to guide animals toward the designated crossings.

Officials are still working to make the bridge more inviting by adding vegetation.

And the benefits extend beyond wildlife.

Fewer collisions mean fewer injuries and deaths, less vehicle damage, reduced emergency response costs, and fewer traffic delays.

But for Marette, one particular moment captured the true meaning of the project.

"One of the most heartwarming moments for me was when CDOT sent me a picture of an elk mama taking her calf under I-25," he said.

After six years of planning and collaboration, that image made it all worthwhile.

"All the hard work for six years all came to fruition in that one moment," Marette said. "That elk with her calf was just standing there in safety, getting to the other side of I-25."

Now, Colorado officials hope to bring similar wildlife crossings to other parts of the state, creating safer roads for both people and animals.

As Laura Sanford, executive director of the Douglas Land Conservancy, put it:

"It's something that is one of the most altruistic things you can do because it's not just for you; it is for everyone."