Yellowstone National Park, as well as many other national parks and national monuments, will waive entrance fees this weekend to recognize Martin Luther King Day on Monday. First of 2012's free entrance days:

"It's the first of several days the national parks are offering to give people a chance to enter parks for free, so they can have a great national park experience."

Yellowstone Spokesman Al Nash said if people want to drive into Yellowstone, it's a little more challenging in winter.

North entrance for drivers:

"It is a little more challenging this time of year. If you're driving your own personal vehicle, you can drive through the park's north entrance at Gardiner, Montana, go into Mammoth Hot Springs and drive out to Cooke City. If you want to get in through our other entrances, you need to make arrangements to enter on a commercially guided snowmobile or snow coach trip."

Those snow coach and snowmobile operators will still want money for their services, and other fees such as parking will probably still apply, says Nash, but entrance is free of charge. So how much is that entrance fee?

Normal entrance fee:

"It's 25 dollars for a seven-day pass to bring your car and your friends into Yellowstone and Grand Teton."

There will be no entrance fee from Saturday through Monday, January 16th, which is a federal holiday.