Great Outdoors Month celebrates the joys of spending time outside. Summer is the perfect time of year to get outside and enjoy recreational activities, such as fishing, biking and hiking.

Each year, more than 2 million people visit one of the most famous — and longest — hiking trails in America: the Appalachian National Scenic Trail. Often referred to simply as the "Appalachian Trail" or just the "AT," the Appalachian Trail extends from Springer Mountain in Georgia to Mount Katahdin in Maine.

At approximately 2,181 miles long, the AT is the longest continuously marked footpath in the world. Hikers follow the AT by using maps and keeping an eye out for marks on trees called "paint blazes."

As it follows the Appalachian mountain range, the trail passes through the states of Georgia, North Carolina, Tennessee, Virginia, West Virginia, Maryland, Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Vermont, New Hampshire and Maine. Virginia boasts the most miles of trail (about 550 miles), while West Virginia claims the least (only 4 miles).

Each year, about 2,000 people try to hike the entire length of the AT in a continuous journey. These people are called “thru-hikers," and only about one out of every four successfully completes the challenge.

Most thru-hikers start in Georgia in the spring and finish in Maine in the fall, taking on average about six months to complete the journey. To help thru-hikers on their journey, the AT features more than 250 three-sided shelters, each usually spaced about a day's hike away from the next.

Most shelters have special food hangers that hikers can use to hang their food bags out of the reach of rodents. Hikers call these contraptions “mouse trapezes."

Completing a thru-hike is quite an accomplishment. The sheer length of the trail isn't the only challenge, though. As it follows the ridgeline of the Appalachian Mountains, the AT runs mostly through wilderness. Hikers will face rough terrain nearly the entire length of the trail, including steep climbs, rocky gorges, and stream crossings.

Because hikers are climbing up and down mountains for thousands of miles, the total elevation gain of hiking the entire length of the AT is about the same as climbing Mt. Everest 16 times! That's 16 times 29,028 feet!

Other dangers include unpredictable weather and wild animals. Although it's possible to see black bears, poisonous snakes, elk and moose along the trail, the most common pests are mice and bugs, such as ticks, mosquitoes and black flies.

Much more common than thru-hikers, “section hikers" tackle the AT one section of trail at a time. Since the trail has hundreds of different access points and parts of the trail are within a few hours' drive of millions of Americans, the AT is also a popular destination for day hikers.

The AT is maintained by a combination of federal, state and local organizations. Each year, thousands of volunteers spend up to 200,000 hours maintaining the trails and the shelters.

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Be sure to check out tomorrow’s Wonder of the Day before it’s going… going… gone!