The U.S. is home to 61 national parks, and each one has something special about it. If you're pressed for time, though, you may want to turn your attention to the 10 most popular parks. These destinations saw the highest attendance of any national park in 2018, according to a list compiled by the National Park Service. From Acadia to Zion and the Rockies to the Smokies, here are just some of the factors that make the 10 most-visited parks so unique.

1. Great Smoky Mountains National Park is the salamander capital of the world.

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Location: Western North Carolina and Eastern Tennessee
Total visitors in 2018: 11,421,200

This sprawling national park in the Smokies might be the most visited because it's also one of the most accessible, considering that it's located roughly within a day's drive of one-third of the U.S. population. The biodiversity is also undoubtedly a draw. Great Smoky Mountains National Park has been dubbed the "salamander capital of the world," and it's home to 30 different species of "spring lizard," as they're called in Appalachia, including the largest one in North America—the hellbender.

2. Grand Canyon National Park visitors could see a sea of clouds.

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Location: Northern Arizona
Total visitors in 2018: 6,380,495

Everyone knows the Grand Canyon, and for good reason—but did you know that its drastic landscape is capable of influencing the weather? Sharp changes in elevation mean that different parts of the park experience totally different weather conditions. North Rim is the coldest, wettest area in the region at an elevation of more than 8200 feet, but just 8 miles away lies Phantom Ranch, the hottest and one of the driest areas at 2460 feet. If you’re lucky, you may be able to witness a rare weather phenomenon called "total cloud inversion," which sometimes occurs at the Grand Canyon when cool air gets trapped beneath a layer of warm air creating a virtual sea of clouds.

3. Rocky Mountain National Park has the highest continuous paved highway in the U.S. running right through it.

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Location: Northern Colorado
Total visitors in 2018: 4,590,493

As the third most-visited park in the U.S., Rocky Mountain sees a lot of foot traffic. Visitors can also drive along the scenic Trail Ridge Road, which has been called the "highway to the sky" because it soars two miles above sea level at its highest point. This 48-mile strip connects Grand Lake and Estes Park and delivers unparalleled views of the forests, tundra, and meadows below.

4. Zion National Park has its very own "Subway."

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Location: Southwest Utah
Total visitors in 2018: 4,320,033

Only the adventurous can traverse The Subway in Zion National Park. To get to this tunnel carved out of rock, visitors must hike for 9 miles (round-trip), scramble over boulders, climb down waterfalls, and swim through creeks—"and the water is cold," according to Utah.com. The tubular landmark not only looks like a subway tunnel, but it also sounds like one, with the rushing water resembling the roaring sound of a subway as it pulls up to the station.

5. Yellowstone National Park once had a "bear lunch counter."

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Location: Northwest Wyoming, Southern Montana, and Eastern Idaho
Total visitors in 2018: 4,115,000

Hungry black and grizzly bears used to feast on trash at an open-air dump in Yellowstone. These "bear shows" were a popular tourist activity between 1890 and the 1940s, and the park eventually installed wooden bleachers for spectators and a sign that read "Lunch Counter—For Bears Only." Unsurprisingly, this set-up was a recipe for disaster. Several park visitors were injured, and the feeding grounds ultimately closed to the public during World War II. The dump itself was shuttered in the '70s, and all waste is now removed from the park.

6. Yosemite National Park's "Firefall" was a huge spectacle for nearly a century.

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Location: Central California
Total visitors in 2018: 4,009,436

In 1872, a local hotel owner by the name of James McCauley tossed campfire embers over the top of Yosemite's Glacier Point, inadvertently creating a cascading "firefall" that looked pretty spectacular from a distance. Thus, a tradition was born, and each summer evening at 9 p.m. sharp, someone would shout "Let the fire fall!" before pushing embers over the edge. These shows were banned from 1913 to 1917, and again during World War II, but they weren't officially eliminated until 1968. The National Park Service said the man-made attraction was better suited to Disneyland than the natural world, and reasoned that the huge crowds also damaged local meadows.

7. For part of the year, Acadia National Park's Cadillac Mountain is the first place in the U.S. to see the sunrise.

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Location: Maine's Mount Desert Island
Total visitors in 2018: 3,537,575

If you want to be the first person in America to see the sunrise, visit the top of Acadia's Cadillac Mountain between October 7 and March 6. The 1528-foot peak is the highest point along the North Atlantic, making it a great vantage point to watch the Atlantic Ocean's glistening waters as they're bathed in sunlight. At other points in the year, the first sunrise can be viewed from either West Quoddy Head or Mars Hill, both of which are also in Maine.

8. Grand Teton National Park's name is a reference to boobs.

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Location: Northwest Wyoming
Total visitors in 2018: 3,491,151

To 19th-century French-Canadian fur trappers, three of the highest mountain peaks in what is now Grand Teton National Park apparently looked like the female form. They called them les trois tétons, which translates to "the three breasts" or "the three teats." It's believed that the trappers were referring specifically to Grand Teton, Teewinot Mountain, and Mt. Owen. At any rate, the name stuck and was later anglicized.

9. Olympic National Park is home to one of the world's few temperate rainforests.

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Location: Washington's Olympic Peninsula
Total visitors in 2018: 3,104,455

Temperate rainforests can be found in just a few places around the world, including Chile, New Zealand, Australia, and America's Pacific Northwest. Thanks to all the moisture coming from the nearby Pacific Ocean, swathes of Olympic National Park are a lush oasis of mosses, ferns, lichens, and Sitka spruce.

10. Glacier National Park has some residents who love visitors: the mountain goats.

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Location: Northwest Montana
Total visitors in 2018: 2,965,309

Mountain goats are perfectly at home along the rugged terrain of Glacier National Park. They can scale slopes at a 60-degree angle and withstand temperatures as low as -50 degrees Fahrenheit, plus winds of 100 mph. (Confusingly, though, they're not actually goats at all. Rather, they're more closely related to gazelles and African antelope.) If you want to see these nimble mascots of Glacier National Park, you can head to Goat Lick Overlook, where the animals come to lick the salty, mineral-rich cliffs. Or, just go about your merry way and you'll surely see a few—the Glacier goats have learned that staying in the general vicinity of humans keeps them safer from predators.