North America's largest wildlife overpass opens in Colorado

Rocky Mountain bighorn sheep, elk, pronghorn and other wildlife can now safely cross six lanes of interstate traffic near Larkspur, Colorado, thanks to the completion of the I-25 Greenland wildlife overpass.

The Colorado Department of Transportation recently completed the 200-foot-wide structure — now the largest wildlife overpass in North America. Finished with native soil and vegetation, the overpass reconnects more than 39,000 acres of habitat on either side of I-25, restoring a critical migration corridor that had long been severed by traffic.

Developed in collaboration with Douglas County and land trust partners, including Douglas Land Conservancy and Colorado Cattlemen’s Agricultural Land Trust, the overpass is part of a broader network of wildlife crossings and fencing designed to reconnect large tracts of open space along southern Douglas County’s I-25 corridor.

The Greenland overpass was specifically designed as a wide, open crossing to accommodate species such as elk and pronghorn that use open overpass structures more readily than narrow, enclosed underpasses.

“The I-25 Greenland wildlife overpass is not only an engineering achievement, it is a testament to what is possible when we come together to protect the resources that define Colorado,” said Erik Glenn, chief executive officer of Colorado Cattlemen’s Agricultural Land Trust.

The overpass closes a 3.7-mile gap between existing wildlife crossings and completes the I-25 South Gap project. Before construction, the corridor averaged one wildlife-vehicle collision per day during peak migration seasons. CDOT estimates the completed system could reduce wildlife-vehicle crashes by up to 90%.

“Working in partnership with so many different organizations to accomplish such an amazing conservation project is humbling,” said Laura Sanford, executive director of Douglas Land Conservancy. “So many people from a variety of interests came together for our wildlife.”