|Zion National Park, Utah|
On August 25 you can visit any national park in the United States for free. The date happens to coincide with the 99th anniversary of the National Park Service and to celebrate the anniversary they're letting us in for free. The National Park Service has a website called Find Your Park that'll help you explore and discover new places to check out near you. If you happen to live near the Great Smoky Mountains National Park, you can visit that park for free every day since there isn't a park admission. But, this discount would be huge if you happen to be visiting Utah, home to some of the greatest national parks with each charging $20 or more per car to enter.
For more information about August 25th and which parks you can visit for free, check out the National Park Service's page.