Moose, elk, black bears, and mountain lions can now safely cross six lanes of Interstate 25 near Larkspur, Colorado, thanks to the opening of North America's largest wildlife overpass. The Greenland Wildlife Overpass, measuring 200 feet wide and 209 feet long, covers 41,800 square feet — making it one of the largest bridge structures for wildlife anywhere in the world.

A Bridge for the Wild

The Colorado Department of Transportation completed the structure in Douglas County, covering the overpass surface with dirt, native vegetation, and landscaping designed to look and feel natural to the animals that use it. The goal: make the crossing so seamless that wildlife barely notices they're walking over a six-lane highway with 100,000 vehicles passing below each day.

The overpass connects 39,000 acres of habitat on both sides of I-25 between Larkspur and Monument, and completes a larger system of five smaller underpasses constructed along an 18-mile stretch near Castle Rock. Prior to the system being built, there was an average of one wildlife-vehicle crash per day during fall and spring, when animals are most active.

"The I-25 Greenland overpass is a momentous feat," said Colorado Governor Jared Polis. "Colorado is leading the way in reducing wildlife-vehicle collisions and protecting critical habitat for generations to come."

Built Fast, On Budget

In a rare feat for major infrastructure, the overpass was completed in less than a year — ahead of schedule and on budget. The total construction cost came in at $15 million, with the bulk funded through a federal Wildlife Crossings Pilot Program grant. The project was a multi-agency public-private partnership involving the Federal Highway Administration and Colorado Parks and Wildlife.

Transportation Director Shoshana Lew said the entire wildlife crossing system, called the I-25 South Gap Project, is expected to reduce wildlife-vehicle crashes along the corridor by 90 percent.

Proven Results

Colorado's investment isn't based on hope — it's backed by data. The state's research shows that the five underpasses already in the system are being successfully used by both large and small mammals. Camera traps have captured footage of deer, elk, and even bears using the passages regularly.

Seventy-six girders hold up the bridge deck, providing enough width for big game animals — moose, bears, mountain lions, elk, mule deer, and pronghorn — to pass comfortably. Guide fencing along the edges directs animals toward the crossing and prevents them from attempting to cross the highway at ground level.

A Growing Movement

The Greenland overpass joins a growing network of wildlife crossings across North America. Utah recently celebrated the success of its first wildlife bridge, and Los Angeles is building what will be the world's largest wildlife crossing over the 101 freeway. The movement reflects a shift in how transportation planners think about roads — not just as human infrastructure, but as barriers that fragment ecosystems.

"After more than nine years of planning and work, Colorado Parks and Wildlife is excited," said Wildlife Manager Matt Martinez. "We look forward to deer, elk, bears, mountain lions, and many other species safely crossing I-25, once a major barrier to migration and wildlife movements."

It's a simple idea — build a bridge so animals don't have to dodge traffic — and it's working.