At Glacier National Park, exactly when in summer the Going-to-the-Sun Road will be open end-to-end is hard to predict, due to the heavy snows that fall along the Continental Divide there.

In Yellowstone National Park, a schedule determines when the road over Sylvan Pass will open in spring -- this year, the schedule calls for the route to be open from Lake to the East Entrance by May 3, although if the budget sequestration takes effect that could be delayed until June  -- and park crews try to adhere to it.

With artillery rounds.

Two national parks in the Rocky Mountains, two very different approaches to clearing away winter's snows to make way for summer visitors.

“Every day," Yellowstone Superintendent Dan Wenk said last week when asked if he struggles, philosophically, with using 105 mm howitzers to bomb a pass in the world's first national park so perhaps 100 snowmobiles and snowcoaches can safely motor over it.

This is how crews in Glacier work to remove snow from the Going-to-the-Sun Road. NPS photo.

"One of the questions I asked shortly after I arrived in Yellowstone was if we didn’t use howitzers on Sylvan Pass in the winter, would we use them to open the road in the spring?" the superintendent continued. "And the answer I was told was 'yes.' The howitzers are being used not only for keeping access over Sylvan Pass in the winter, but they’re also used to open the road in the spring. I think that’s a question that we’ve had numerous discussions with the stakeholders on the east side of the park. Do I struggle with it? yes I do.

“I would love to find a way to provide the access that we need without having to do that.”

At Glacier, crews rely on gravity and sunshine to help clear the Sun Road. They do employ quite a few snowplows, bulldozers, and other heavy equipment to move the snow off the road, beginning, if possible, in April and winding up, if possible, sometime in June, and sometimes in July.

But they don't use bombs.

In Yellowstone, Superintendent Wenk alludes to the political pressures "on the east side of the park" that play a role the ongoing use of howitzers, both to keep Sylvan Pass open in winter and cleared off in spring. He said there have been discussions about moving toward the approach Glacier uses with the Sun Road in spring.

This is what Yellowstone crews use to clear avalanche chutes above Sylvan Pass.

"Those are, as you might imagine, very difficult discussions," he said.

Political influences are common throughout the National Park System, but they can be particularly strong undercurrents in Yellowstone, as Superintendent Wenk's predecessor, Susan Lewis, discovered when she tried to approve a winter-use plan that did not include keeping Sylvan Pass open.

Ratcheting up the political pressure was the fact that the occupant of the vice president's office at the time was from Wyoming, Dick Cheney.

A new book from Michael J. Yochim, Protecting Yellowstone, Science and the Politics Of National Park Management, recounts what then-Superintendent Lewis encountered.

Upset over the possible loss of motorized winter access to Yellowstone over Sylvan Pass, Cody residents and Wyoming congressional representatives reacted strongly. Opposition sprang up form citizens groups in the Cody area, as well as from all levels of Wyoming government (city, county, and state). It did not take long before Vice President Cheney heard from his former neighbors. As Cheney later added:

"We did work with the Park Service. My office was contacted by folks from Cody. I talked to Colin Simpson (Cody state senator and son of Alan Simpson). I'm familiar generally with the importance of that east entrance to folks in Cody, the business community there. I recommended that my staff work on trying to keep that entrance open. As vice president, I don't run anything. I'm not in charge of the Park Service, but I can make suggestions, and my staff is actively involved in a lot of those issues on my behalf."

Cheney understated his influence, for just a few months later Yellowstone's managers changed their plans and decided to continue their avalanche-control program with only minor changes. They would close Sylvan Pass about ten days earlier in spring than the rest of the park roads, to save a small amount of funding, but the safety issues were not addressed in any significant manner. Park employees continue to travel under the uncontrolled avalanche zones to reach the howitzer.

Those politics continue today, and until they wane Yellowstone crews will shuttle between 100 and 300 55-pound artillery rounds to Sylvan Pass each year for use in winter avalanche control and spring snow removal. And come summer, they'll mark the hillsides above the pass off-limits to hikers, just in case there might be a stray round or two that didn't detonate.