The entry fees being waived range from $3 to $25 but it doesn’t apply to fees charged for camping, reservations, tours or concessions.

August 15-16 will be the last weekend this summer that the National Park Service is offering this free admission. The other weekends were June 20-21 and July 18-19.

All 391 national parks across the country will be free. For more info, visit NPS.gov.