The National Park Service is offering another fee-free day coming up to celebrate Earth Day this weekend. The National Park Service says entrance to national parks like the Grand Canyon will be free tomorrow and Sunday. There will be many Earth Day activities for the family to enjoy. The activities are free and open to the public and will take place at the Grand Canyon Visitor Center plaza near Mather Point. One activity is litter clean-up at the park. For more information, log onto the Grand Canyon’s website.