Colorado's $15 Million Wildlife Overpass, Largest in North America, Cuts I-25 Collisions by 91 Percent
In December 2025, a $15 million wildlife bridge was inaugurated near Monument, Colorado, marking the completion of a mitigation system that spans 18 miles of Interstate 25 between Castle Rock and Monument, located approximately 50 miles south of Denver. This bridge, the largest of its type in North America, is 200 feet wide and 209 feet long, crossing six lanes of traffic. The initiative started in 1996, which included the installation of 14 miles of fencing and five wildlife underpasses. From 2022 to 2024, wildlife-vehicle collisions decreased by 85 percent annually, with a 91 percent reduction in the final year. Since the bridge's opening, only two accidents have been reported, and travel delays have decreased by 9 percent. Plans for six more crossing systems statewide are underway, one of which will cater to Rocky Mountain bighorn sheep.
Key facts
- The $15 million Monument overpass opened in December 2025 and is described by officials as the largest wildlife crossing of its kind in North America
- The bridge spans six lanes of Interstate 25, measures 200 feet wide by 209 feet long and covers about 41,800 square feet, just under an acre
- Construction of the corridor's mitigation system began in 1996 with 14 miles of eight-foot fencing and five underpasses between Castle Rock and Monument
- Wildlife-vehicle collisions on the corridor dropped about 85 percent per year on average from 2022 to 2024 and 91 percent in the final year
- Only two wildlife-vehicle accidents have been reported in the ten months since the overpass opened
- Travel delays along the stretch fell roughly 9 percent
- Pronghorn were recorded on the west side of I-25 for the first time in decades, and elk, rabbits and northern leopard frogs have used the bridge
- Colorado plans six more crossing systems, including the first designed for Rocky Mountain bighorn sheep
- California's $114 million crossing over Highway 101 in Los Angeles County is expected to open in December
Entities
Artists
- Brandon Marette
- Chuck Attardo
- Bridget O'Rourke
- Savannah Eller
- Olivia Young
- Olivia Prentzel
- Sarah Kuta
Institutions
- Colorado Department of Transportation
- Colorado Parks and Wildlife
- Colorado Politics
- CBS Colorado
- The Colorado Sun
- Smithsonian Magazine
- CBS News
- Colossal
Locations
- Colorado
- United States
- Interstate 25
- Castle Rock
- Monument
- Denver
- Trinidad
- Greenland
- California
- Los Angeles County
- Highway 101
- Colorado Springs