In The NoCo

Colorado is building the world’s largest ‘wildlife overpass.’ Here’s how it will help animals – and drivers – along I-25

By In The NoCo,

Published October 29, 2025 at 5:35 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. It will help prevent vehicle-wildlife crashes that average one per day on the stretch of highway.

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.

The Greenland wildlife crossing is being built 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 per 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 earlier this year to explain how they work – and why they’re important to both wildlife and drivers. We’re listening back to that conversation today.

For more on interactions between humans and Colorado wildlife, check out this series from KUNC News.

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In The NoCo

KUNC's In The NoCo is a daily slice of stories, news, people and issues. It's a window to the communities along the Colorado Rocky Mountains. The show brings context and insight to the stories of the day, often elevating unheard voices in the process. And because life in Northern Colorado is a balance of work and play, we celebrate the lighter side of things here, too.

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Erin O'Toole

As the host of KUNC’s news program and podcast In The NoCo, I work closely with our producers and reporters to bring context and diverse perspectives to the important issues of the day. Northern Colorado is such a diverse and growing region, brimming with history, culture, music, education, civic engagement, and amazing outdoor recreation. I love finding the stories and voices that reflect what makes NoCo such an extraordinary place to live.

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Brad Turner

Brad Turner is an executive producer in KUNC's newsroom. He manages the podcast team that makes In The NoCo, which also airs weekdays in Morning Edition and All Things Considered. His work as a podcaster and journalist has appeared on NPR's Weekend Edition, NPR Music, the PBS Newshour, Colorado Public Radio, MTV Online, the Denver Post, Boulder's Daily Camera, and the Longmont Times-Call.

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Ariel Lavery

Ariel Lavery grew up in Louisville, Colorado and has returned to the Front Range after spending over 25 years moving around the country. She co-created the podcast Middle of Everywhere for WKMS, Murray State University’s NPR member station, and won Public Media Journalism awards in every season she produced for Middle of Everywhere. Her most recent series project is "The Burn Scar", published with The Modern West podcast. In it, she chronicles two years of her family’s financial and emotional struggle following the loss of her childhood home in the Marshall Fire.

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