On Tuesday, December 16, 2025, the largest wildlife crossing in North America was completed, reaching over I-25 at  200 feet wide and 209 feet long. The crossing is in Douglas County, Colorado, between Castle Rock and Monument, and is named the I-25 Greenland Wildlife Overpass.

According to the Colorado Department of Transportation (CDOT), the overpass is essential to animals like elk, pronghorn, mule deer, black bears, mountain lions, and many other species in the Front Range. It allows the animals to safely migrate and access food on the 39,000 acres of land on either side of the freeway.

CDOT Executive Director Shoshana Lew says that the crossing “is expected to reduce wildlife-vehicle crashes by 90%.” The overpass is a part of a system of wildlife crossings along I-25, and before its completion, “there was an average of one wildlife-vehicle crash a day in the fall and spring wildlife movement seasons,” says CDOT. One animal doesn’t sound like a lot, but with 100,000 vehicles traveling the area every day, it can be extremely dangerous.

The success of the I-25 Greenland Wildlife Overpass, along with other wildlife crossings, has influenced other states to begin conversations about building wildlife crossings. Within the next few years, there could be wildlife crossings across interstates around the country.