It took some shots from a 105mm howitzer to clear some potential avalanches, but Yellowstone National Park crews were able Tuesday to open the park's East Entrance for over-snow travel as scheduled.

Park officials say the entrance, which lies 53 miles west of Cody, Wyoming, the closest town to the entrance, was opened at 8 a.m. MDT for traffic. No word on whether any snowmobilers or snowcoaches were waiting to enter the park at that time.

Yellowstone officials say crews used a howitzer to conduct avalanche hazard mitigation operations on Thursday, December 17, and again on Monday, December 21. Several natural avalanches had occurred prior to these missions, according to the park. Additionally, several large and medium avalanches ran to or across the East Entrance road during avalanche mitigation work. "After these missions were completed, the East Entrance road was packed and groomed for motorized over-snow travel," the park reported.

Commercially guided snowmobiles and snowcoaches are allowed to travel between Pahaska Tepee and Fishing Bridge Junction over Sylvan Pass when weather and avalanche conditions permit.

Now, Yellowstone officials had initially decided back in 2007 not to maintain the route over Sylvan Pass for winter travel, saying it was too dangerous (some 20 avalanche chutes tower over the pass) and too few people were using it to justify the cost. However, Wyoming's clout -- at the time, Dick Cheney, a Wyoming resident, was vice president of the United States -- had the final say on the matter, and the Park Service agreed to maintain the route between December 22 and March 1 if snow conditions permitted, if safety could be maintained, and if equipment was available to groom the route.

At the time the decision to maintain the pass was made, it was said that keeping Sylvan Pass safely open in winter could cost Yellowstone nearly $4 million if all Occupational Safety and Health Administration concerns were addressed, according to those who have carefully followed the issue. That total includes $3.46 million in one-time costs and $456,216 in recurring annual operational costs.

In other words, the preferred Sylvan Pass plan endorsed by the Park Service was four times Yellowstone's 2008 budget increase.

During the winter of 2007-08, 463 people traveled over Sylvan Pass from Cody. At that rate, based on the nearly $4 million Yellowstone soon could find itself spending to keep Sylvan Pass safe, the cost would equate to $8,470.76 per person.