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America’s crown jewels - From Yosemite to Yellowstone, the US national parks are usually a source of pride and wonder.

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What went wrong? - Something wicked lurks beneath this majestic wilderness.

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The numbers don’t lie - Since the National Park Service was founded in 1916, over 1,000 people have vanished without a trace on the federal grounds.

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There’s a lot of land - A total of 84.9 million acres have been designated national park land, which makes up approximately 3.6% of all land in the US.

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There has yet to be thorough federal research - The National Parks Service often leaves it to local law enforcement to track and solve the cases of missing persons, or to mark them as cold.

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Cold case: Stacy Ann Arras -

The internet is obsessed with the unsolved mystery of the girl who, on a horseback riding trip in Yosemite, went off to take a photo by the water then vanished, leaving nothing but her camera lens behind.

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One among many - There are countless stories of people leaving for hikes and never returning, and even some where the bodies are actually found, but in areas that had already been extensively searched.

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A particularly bizarre case - A toddler was found dead 12 mi from where he vanished, over two mountain ranges and numerous creeks, which he could’ve never traversed himself.

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Are there commonalities? - Stacey Ann Arras’s disappearance, untraceable even to a trained rescue dog's nose, along with hundreds of others, comprise a strange array of seemingly unsolvable national park vanishings.

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Of course, some can be explained - Tragic accidents are inherent risks of exploring the wilderness. Drowning is the most common accident, but there’s also dangers like falling from the peak of a mountain, animal attacks, and extreme weather.

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The cases in question aren’t so clear cut - In one case, a physician, in excellent physical condition and equipped with new snow gear, went hiking to a winter cabin with his friends. What could go wrong?

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An entirely unpredictable fate - After going a short distance ahead on a trail, he vanished. His body was found two weeks later, miles away, hundreds of feet higher in elevation, with all his snow gear and emergency equipment and provisions unused, and his shoes nowhere to be found.

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Enter David Paulides - The cryptozoologist and former police detective introduced a new theory that has quickly taken hold of many.

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He created his own database - Paulides showed particular interest in the cold cases involving the National Parks Service, and began compiling any data he could collect to look for trends.

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What he found intrigued and disturbed him - Particularly in cases where people appeared to vanish into thin air, he noticed that the rescue dogs either could not or would not perform their duties.

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Trends in location - He found that several of the disappearances happened near berry patches and boulders, and that in many cases people were found at much higher altitudes than those at which they disappeared.

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He found geographic hot spots for disappearances - Paulides documents many of the cases in his book series ‘Missing 411,’ which he uses to highlight 52 clearly defined geographic "clusters."

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Some hot spots include: - The Rocky Mountains and Sierra Pacific range, as well as Colorado, Michigan, Georgia, and Arkansas.

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So what does he think happened to them? - Well, Paulides points to none other than Bigfoot, a hairy, ape-like giant that dwells in the wilderness and snatches up unsuspecting victims.

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Also known as the Sasquatch - Paulides, among many others, uses the mysterious circumstances of these cold cases as potential evidence for the existence of these creatures.

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Others point to the Wendigo - The Wendigo is an evil spirit from Algonquin folklore, popular in Canada as well, who terrorizes forests and can possess humans, causing them to have cannibalistic urges.

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His only conclusion after 7,000 hours of research -

After interviewing families, law enforcement, and search-and-rescue personnel, poring over newspaper archives, and submitting hundreds of Freedom of Information Act (FOIA) requests, all signs pointed to Bigfoot.

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He’s not alone in this belief, but he's one of the most serious - Paulides reportedly submitted a FOIA request for records related to two missing hikers in Great Smoky Mountains National Park and noted on the request: "Associated with possible Bigfoot abduction."

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It’s hard to deny there’s something unnerving -

These theories have been criticized for many reasons, including their failure to let loved ones properly grieve.

Whether you believe the supernatural theories or not, the unsolved cases do hint at something very wrong.

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The most disturbing part of all - Despite the controversy, Paulides’ research did discover something scary: the fact that the National Park Service doesn't keep track of missing persons, and can’t even name exactly how many people have disappeared.

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A call for action - With the revelation that there is no federal-level database tracking how many people go missing from federal lands, Paulides’ work kick-started a petition to hold the National Park Service responsible.

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Perhaps more reasonable trends can be found - With a federal database, hopefully commonalities will be easier to pinpoint, and the rate of disappearances will decrease.

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But for now -

Take great care when traversing the stunning but dangerous land, and always let people know where you are!

See more: The most dangerous cities in America

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