Although Yellowstone is one of the biggest national parks in the US, most tourists gather around its most iconic sites.
Over three million people visit Mount Rushmore each year to see the sculptures of four famous American presidents.
Central Park is touted as New York City's 'green lung' for a reason – its beautiful 843 acres are hard to match.
Still, they both have stunning blue lakes, snowy peaks, fir-covered slopes, and glaciers.
There are few places on Earth quite like the Las Vegas strip with its all-you-can-eat buffets, bustling casinos and glitzy hotels.
Arizona's Grand Canyon draws millions each year: in fact, its visitor numbers are usually second only to those of the Great Smoky Mountains.
Knott's Berry Farm is a smaller alternative to Disney California Adventure Park, one of the state's main attractions.
Half Dome (shown) is a popular walk that rises 5,000 feet above the Yosemite Valley and provides stunning vistas.