How North America is Rebuilding Its Fragmented Wildlife Corridors

Interstate 90 is the longest highway in the United States, spanning more than 3,000 miles from Seattle to Boston. But for the wildlife living in the Snoqualmie Pass of Washington State, the highway is a massive, lethal concrete divide. Every 26 seconds, a driver in the U.S. hits an animal. These collisions kill up to two million large animals annually, cause hundreds of human fatalities, and generate more than $8 billion in economic damages. For decades, the solution was simply to put up warning signs. Today, North America is embracing a permanent, structural fix: wildlife crossings.[4]

Wildlife crossings are specialized infrastructure—ranging from vegetated overpass bridges to subterranean culverts—designed to stitch fragmented ecosystems back together. They are not merely a safety measure for motorists; they are a biological necessity. When highways bisect a forest, animal populations become isolated. "Because you lose genetic variability," explains Patty Garvey-Darda, a U.S. Forest Service biologist, "gradually you start getting localized extinction, and populations get further and further apart, and smaller."[4][6]

The mechanism behind a successful crossing relies on behavioral psychology as much as structural engineering. Animals do not naturally seek out concrete bridges. To make the crossings effective, engineers install miles of high fencing along the highway to funnel wildlife toward the safe passage. Once there, the structures are landscaped with native plants, soil, and rocks to mimic the surrounding environment. High concrete walls block the glare of headlights and muffle the roar of semi-trucks, allowing animals to cross without realizing they are traversing a major interstate.[4][6]

The undisputed gold standard for this infrastructure is Banff National Park in Alberta, Canada. Decades ago, the Trans-Canada Highway was a death trap for local fauna. Today, a network of 38 underpasses and six overpasses spans the highway. The results have been staggering: wildlife-vehicle collisions in the park have plummeted by 80 percent. The Banff model proved that if you build it—and fence it correctly—they will indeed come.[4][6]

Inspired by Banff, the concept has scaled into one of the most ambitious conservation projects in human history: the Yellowstone to Yukon (Y2Y) Conservation Initiative. Stretching 2,000 miles from Wyoming to the Canadian Arctic, the Y2Y corridor aims to create a continuous "wildway" along the spine of the Rocky Mountains. By the start of 2026, the initiative and its partners had successfully installed 204 wildlife crossings across the region, effectively reconnecting landscapes that had been severed for a century.[1][6]

The ecological dividends of the Y2Y mega-corridor are already measurable. In 1993, grizzly bear populations in the lower 48 states were separated by 150 miles of hostile, human-dominated terrain—a gap that threatened their genetic viability. By 2025, strategic land purchases and new highway crossings had shrunk that gap to just 45 miles. In southeast British Columbia alone, conservationists recently secured 112,000 acres of land to ensure the corridor remains unbroken.[1][6]

The push for connectivity is not limited to the lush forests of the Pacific Northwest or the Canadian Rockies. In the arid expanses of Nevada and Arizona, Highway 93 serves as a primary trade route connecting Canada, the U.S., and Mexico. It also cuts directly through the historic migration routes of the desert bighorn sheep and mule deer. A network of overpasses completed over the last decade has recorded tens of thousands of successful animal crossings, reducing motorist crashes by nearly 90 percent in targeted zones.[5][6]

Designing these corridors requires immense precision. Conservationists look for "pinch points"—natural bottlenecks where topography forces wildlife into a narrow geographic band. They also analyze traffic volume. Roads carrying fewer than 2,500 vehicles a day pose a low barrier, but highways with over 10,000 vehicles daily act as a total wall, where animals simply give up trying to cross. Identifying where a pinch point meets a high-volume road dictates exactly where a multi-million-dollar overpass must be built.[3][6]

As the climate warms, the need for these corridors is becoming urgent. Species are being forced to migrate northward or to higher elevations to track shifting temperature bands. If their escape routes are blocked by impassable highways, entire populations could collapse. Recognizing this, a landmark 2026 study published in the journal FACETS mapped ecological connectivity across the entire U.S.-Canada border—the longest terrestrial boundary in the world.[2][6]

The researchers utilized "circuit theory modeling," a spatial ecology technique that treats the landscape like an electrical grid. Human development and highways act as "resistance," while natural forests and rivers act as conductive pathways. The resulting high-resolution map identified the exact transboundary corridors where wildlife movement is concentrated, providing a blueprint for where the U.S. and Canada must coordinate their next wave of infrastructure investments to meet global biodiversity targets.[2][6]

Despite the proven success of wildlife crossings, significant hurdles remain. The 2026 mapping study revealed that only about 20 percent of the highest-value connectivity hotspots along the border fall within strictly protected areas. The rest lie on private land, agricultural zones, or indigenous territories. Expanding the corridor network will require voluntary conservation easements from ranchers and deep collaboration with Indigenous nations, who are increasingly co-managing these vital landscapes.[2][6]

Ultimately, the proliferation of wildlife crossings represents a profound shift in how North America manages its infrastructure. Highways are no longer viewed merely as arteries for human commerce, but as obstacles that must be bridged for the continent's original inhabitants. By investing in concrete, fencing, and native vegetation, engineers and ecologists are slowly stitching a fragmented continent back together, ensuring that the ancient migrations of elk, bears, and panthers can continue into the next century.[6]