Every year, the sleepy 2,000 person town of Willow, Alaska is inundated with visitors eager to observe—or partake in—“the Last Great Race on Earth.”

This year, a worrisome new tradition for the Iditarod Trail Sled Dog Race persisted. In 2003, the race route had to be moved from its usual starting point in Willow to Fairbanks because the winter hadn’t provided enough snow for good racing terrain. It was moved again in 2015. This year, a month before the race, officials decided to relocate a third time after determining that snow in three or four sections of the track was not sufficient.

"We're going through some major changes with the environment," Iditarod Race Marshal Mark Nordman told a press conference.