5. Yellowstone National Park, Wyoming, Montana and Idaho
7/11A handful of national parks make up the top 10, including the nation's first national park, Yellowstone. This American icon spans three different states, including Wyoming, Montana and Idaho. The region's unique geothermal features like Old Faithful as well as its spectacular wildlife have propelled it to a perfect five-star rating on TripAdvisor and have inspired more than 10 million annual Google searches.