The North Cascades Highway goes wild for the winter

A rare, yet annual, event took place Thursday night in Washington’s North Cascades.

A roadless area roughly doubled in size.

The Washington state Department of Transportation shut down State Route 20, the North Cascades Highway, at 6 p.m. Thursday for the winter.

The closure inconveniences drivers traveling between eastern and western Washington but reconnects the wildlands north and south of Highway 20.

Avalanche danger beneath the jagged peaks of the North Cascades forces the snowy highway to close each winter.

The effective disappearance of 37 miles of highway beneath a blanket of snow gives wide-ranging carnivores like wolverines and lynx more room to roam for several months.

Those species thrive in roadless landscapes, where disturbance from humans and their motor vehicles is minimal.

The U.S. Fish and Wildlife Service listed the wolverine as a threatened species outside of Alaska on Wednesday, 29 years after environmental groups petitioned the agency to do so.

The agency listed lynx outside of Alaska as threatened under the Endangered Species Act in 2000.

Biologists estimate that fewer than 50 Canada lynx remain in Washington, according to the nonprofit Conservation Northwest.

The wolverine population in the Washington Cascades is probably fewer than 25 individuals, according to the Washington Department of Fish and Wildlife.