Celebrate our national parks the only way you truly can: By visiting on a fee-free day. Head for the hills.

The National Park Service turns 101 on Friday. You can celebrate by heading to any national park for fee-free entrance, but why not say "Happy Birthday" by buying an annual pass? It's the best $80 you'll spend all year, we promise.

We took a look at the list of least-visited national parks to give you a few ideas for sites that need some love. All of these beautiful places count fewer than 30,000 visitors per year. By comparison, Golden Gate National Recreation Area and the Blue Ridge Parkway received more than 15 million visits last year. Great Smoky Mountains National Park had about 11 million visitors, and Grand Canyon had just under 6 million.

So why not check out these rarely-visited parks, where you'll rarely see other humans? If we're missing a lesser-known park you love, we'd love to hear about it! Share your photos on our Facebook page or by tagging @snewsteam on Twitter or Instagram.

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Doug Tompkins, 72, founded The North Face in 1966. Photo credit: Wikimedia Commons

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