North America's Largest Wildlife Overpass Opens Over I-25 in Colorado

A sweeping wildlife overpass arching above Interstate 25 near Larkspur, Colorado, officially opened in late December 2025, becoming the largest wildlife crossing in North America. Named the Greenland Overpass, the structure is a signature project of the Colorado Department of Transportation (CDOT) and reconnects nearly 39,000 acres of protected habitat long divided by the busy highway that links Denver and Colorado Springs.

Elk, mule deer, pronghorn, black bear and mountain lion are all expected to use the overpass, which is wide enough to carry vegetation and a natural-looking landscape across six lanes of traffic. The project also includes miles of wildlife fencing on both sides of the interstate to funnel animals toward the crossing and away from the roadway — a proven combination that in other states has reduced wildlife-vehicle collisions on treated segments by roughly 80 percent.

“Named the Greenland Overpass, the structure is a signature project of the Colorado Department of Transportation (CDOT) and reconnects nearly 39,000 acres of protected habitat long divided by the busy highway that links Denver and Colorado Springs.”

CDOT and conservation partners spent years planning and funding the overpass, combining state and federal dollars with private contributions. The agency says the new crossing addresses one of Colorado's deadliest stretches of road for both drivers and wildlife: collisions along the I-25 corridor through Douglas County had been rising with traffic growth, and several species were being cut off from seasonal range.

The Greenland Overpass is part of a growing continental network of wildlife crossings that includes Banff National Park's iconic overpasses, California's Wallis Annenberg Wildlife Crossing and new projects in Wyoming, New Mexico and Oregon. Wildlife biologists say the Colorado structure will serve as a model — and a research site — for how major transportation corridors can coexist with the big, migratory animals that define the American West.