A few popular national parks in the United States are Great Smoky Mountain National Park, Grand Canyon National Park, Yosemite National Park and Yellowstone National Park. As of 2014, each of these parks had several million visitors. The National Park Service oversees and maintains these and other U.S. national parks.
Great Smoky Mountain National Park lies on the eastern edge of Tennessee and western side of North Carolina, and features the range from which it gets its name, in addition to acres of forest and over 10,000 identified species of plants and animals. The park has over 800 miles of trails, self-guided auto tours and cultural displays.
Grand Canyon National Park in Arizona is the home of the nation's landmark canyon, which visitors can experience either from the top in scenic overlooks or from below by rafting on the Colorado River. Visitors can opt between private and guided rafting trips.
The 5,000-foot granite Half Dome is one of the most famous features of Yosemite National Park. The dome is a popular destination for climbers. Non-climbers can opt to take the cable system to the top.
Yellowstone National Park, the first such park in the nation, is a hotspot for geothermal activity that reveals itself in geysers, hot springs and mud pots. The Old Faithful geyser is among the park's top attractions.