How North America's Expanding Wildlife Corridors Are Saving Billions and Rewilding the Continent

The North American highway system is a marvel of human engineering, but for the continent's wildlife, it represents a deadly and impassable grid. Every year, an estimated one to two million motorists in the United States collide with large animals. These accidents result in roughly 200 human fatalities, 26,000 injuries, and a staggering $8 billion in property damage and emergency response costs.[2][3]

For decades, conservationists and transportation officials viewed this carnage as an unavoidable byproduct of modern infrastructure. However, a quiet revolution in civil engineering and landscape ecology is proving otherwise. Across the United States and Canada, a massive expansion of "wildlife crossings"—purpose-built bridges and tunnels designed exclusively for animals—is reconnecting fragmented ecosystems and virtually eliminating collisions in hotspot areas.[1][7]

The mechanism behind these crossings relies on a combination of structural engineering and behavioral ecology. Wildlife crossings are not simply bridges dropped randomly over highways; they are carefully sited using GPS collar data that tracks historical migration routes and identifies exactly where animals are already attempting to cross. Once a crossing is built, miles of specialized exclusion fencing are installed along the highway to funnel roaming animals toward the safe passage.[3][5]

The infrastructure comes in two primary forms: overpasses and underpasses. Overpasses are wide, vegetated bridges covered in soil, native grasses, and trees, favored by prey species like elk and moose that require open sightlines to spot predators. Underpasses, ranging from large concrete arches to smaller culverts, are often preferred by predators like cougars and black bears, as well as amphibians and small mammals seeking cover.[4][6]

The evidence supporting these structures is overwhelming, with the most robust data emerging from Canada's Banff National Park. Since 1996, Banff has constructed over 40 crossing structures along the Trans-Canada Highway. Long-term monitoring reveals that these crossings have reduced wildlife-vehicle collisions by more than 80% overall, and by an astonishing 96% for deer and elk specifically.[6]

This localized success has inspired continental-scale ambitions, most notably the Yellowstone to Yukon (Y2Y) Conservation Initiative. Stretching 2,000 miles from Wyoming to the Canadian Arctic, the Y2Y region is one of the world's most ambitious rewilding projects. As of early 2026, the initiative and its partners have successfully implemented 204 wildlife underpasses and overpasses across the corridor.[1]

The impact of the Y2Y corridor is measurable in both lives saved and genetic diversity restored. By linking isolated protected areas, the crossings have allowed grizzly bear populations to intermingle, shrinking the geographic gaps between isolated groups from 150 miles down to less than 45 miles. This genetic mixing is crucial for the long-term resilience of the species against disease and the shifting habitats caused by climate change.[1][4]

The momentum is now spreading far beyond the Rocky Mountains. In Southern California, the Wallis Annenberg Wildlife Crossing—the largest in the world—is nearing completion, spanning ten lanes of traffic over U.S. Route 101 to save a genetically isolated population of mountain lions. Meanwhile, the "Reconnecting the Rockies" project in British Columbia is retrofitting Highway 3 with a continuous 36-kilometer network of fencing, underpasses, and a massive new overpass.[5][6]

In the eastern United States, the Appalachian mountain range serves as the region's largest migration corridor. States like Virginia and North Carolina are increasingly retrofitting existing stream culverts and bridges to serve double-duty as wildlife underpasses, a highly cost-effective strategy that avoids the expense of building new standalone structures.[2]

The primary uncertainty surrounding wildlife crossings has historically been their steep upfront cost. A single vegetated overpass can cost anywhere from $5 million to over $20 million, depending on the terrain and highway width. For cash-strapped transportation departments, justifying this expense for animal welfare alone was often a political non-starter.[5][7]

However, the economic calculus has shifted dramatically. Research consistently demonstrates that because wildlife collisions are so incredibly expensive—costing thousands of dollars per incident in vehicle damage, medical bills, and road closures—crossings in high-traffic corridors typically pay for themselves in less than a decade. The societal cost of doing nothing now demonstrably exceeds the cost of construction.[1][2]

Recognizing this return on investment, federal and state governments are unlocking unprecedented funding. The U.S. Infrastructure Investment and Jobs Act dedicated $350 million specifically for a Wildlife Crossings Pilot Program, distributing grants to states and tribal nations. States like Florida, New Mexico, and Wyoming have also passed dedicated legislation, allocating hundreds of millions of dollars to protect corridors and build crossings.[3]

Challenges remain, particularly in retrofitting older highways where adjacent land has already been heavily developed. Furthermore, while animals adapt to the structures remarkably quickly, it can take several years for a local population to fully trust and utilize a new crossing, requiring patience from monitoring teams.[2][7]

Despite these hurdles, the proliferation of wildlife crossings represents a rare, unifying triumph in modern public policy. By merging the priorities of conservation biologists, fiscal conservatives, and public safety advocates, North America is proving that human infrastructure and wild ecosystems can safely coexist.[7]