The world’s largest wildlife overpass will soon span I-25. Here’s how it will help animals – and drivers

Published August 12, 2025 at 5:40 AM MDT

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A concept simulation shows a herd of animals crossing over a wildlife crossing while six lanes of traffic drive fluidly underneath. — The Colorado Department of Transportation is building what will be the world's largest wildlife crossing over I-25 north of Monument and south of Denver. It will help prevent vehicle-wildlife crashes here that average one per day.

The world’s largest wildlife overpass will soon be open for use in Colorado.

Wildlife overpasses allow animals to safely cross over highways. And Western states are building more of them to cut down on the number of crashes between vehicles and animals.

This new overpass is being constructed over a section of I-25 between Denver and Colorado Springs, just north of Monument. Some 80,000 drivers pass through this area daily. But elk, mule deer, and pronghorn also use that area to move between the mountains and the plains. And this stretch of highway averages one vehicle crash involving wildlife every day.

So, how could this overpass help reduce these dangerous and costly crashes?

Nicki Frey is a wildlife specialist with Utah State University Extension. She studies wildlife overpasses in the West, but was not involved in planning this one. She joined Erin O’Toole to explain how they work – and why they’re important to wildlife in the ecosystem.