On these six days, you can visit any national park for free. Here's some dates to remember. The first fee-free day is coming up.

The National Parks Service has announced free entrance days for 2021. On six select days this year, anyone can visit national parks for free. According to the NPS, "fee-free days provide a great opportunity to visit a new place or an old favorite, especially one of the national parks that normally charge an entrance fee."

2021 Fee-Free Days:

Fee-free days do not cover amenities or use fees for activities like camping, boat launch use, transportation, or special tours.

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Winter in Acadia National Park poses unique outdoor recreation opportunities. With the summer crowds long gone, park's many popular hiking trails are less populated. The 45 miles of Carriage Roads are a perfect way to stroll around the park on skis or in snowshoes. When conditions allow, volunteers groom sections of the roads for cross-country skiers. Snowshoers are asked to stay off any groomed tracks.

Unplowed park roads are also great for snowshoeing and cross-country skiing, just watch for snowmobilers. That's right, snowmobiling is allowed on the 27-mile Park Loop Road system. The permitted snow-sled routes also include the road up Cadillac Mountain, and most fire roads.

Learn more about winter visitation at Acadia National Park here.