Surprisingly, the majority of United States National Park units are free to enter all year long.  Only 116 of the 419 National Park Service units charge any sort of entrance fee.  Admission to these parks can range from $5 per person to $35 per vehicle. The national park entrance fees are used to help offset the costs of running the park.  Typically, 80% of each national park fee is used in the park it is paid. I know the National Park Service naming system can be very confusing. But if you are planning on doing any sort of road trip or exploring the outdoors, paying individual national park unit’s entrance…