To the often asked question — "Is it or isn't it?" — the response has been and is — "It is." Yellowstone National Park is open in the winter to snowmobile use.

The gates have never been closed, albeit for a few minutes when the park officially opened in December of 2003 and a tug-of-war ensued between those who wanted the park open and a federal judge, which ended with the park opening.

"Still," said Jerry Johnston, owner of Yellowstone Adventures and former mayor of West Yellowstone, Mont, "people come here and are shocked to learn they can snowmobile into the park. There has been a lot of confusion in recent years."

The park is, in fact, open to winter travel via snowmobile, snowcoach or cross country skis. Restrictions have been placed on snowmobiles in response to complaints over noise and emissions.

Under current requirements, machines must fall under the classification "BAT" or best available technology, meaning they must come with quieter four-stroke engines as opposed to two-stroke, and must meet higher emissions standards.

Even there, said Johnston, there is some confusion.

"The Park Service has said owners can ride their own four-stoke snowmobiles, but not all fall under the BAT classification. What happens is we have to tell owners they can't take that particular machine into the park and, for some, they can't understand why."

All those going into the park must also be accompanied by a guide.

Here, said Clyde Seely, owner of Three Bears Lodge, there is little resistance.

"People pretty much understand and, in fact, find their in-park experience more enjoyable with a guide. They learn a lot about the geology and the biology of the park that they didn't know or were unaware of. Oh, you still get a few who tell us they've been into the park before and know everything, but many of those people come back and tell us how much they enjoy the ride. We get very few complaints."

Here, too, said Johnston, "Many people have told me all they did before was ride into the park and paid little attentions to what was around them. Now they actually take the time to look around and see things they've never seen before.

"Most of my guides grew up in West Yellowstone. They know the area and the history."

For this season and the 2007-08 season the park will operate under actions taken by Congress. An Interior appropriations bill signed in 2005 had a rider that kept in place the authorized use of up to 720 snowmobiles per day into the park and barred the federal courts from intervening.

It also allows for roads inside the park to be groomed on a regular basis but not plowed.