The busy ones have a fee. From the site (linked downthread): >Out of the 418 units in the National Park Service (NPS), 115 parks charge an entrance fee. The m

The busy ones have a fee. From the site (linked downthread): >Out of the 418 units in the National Park Service (NPS), 115 parks charge an entrance fee. The majority of national parks are free! However, the most famous ones -- Yosemite, Yellowstone, Death Valley, Great Smoky, etc -- have an entrance fee.