Summer vacation just got cheaper thanks to the National Park Service.

One-hundred forty-seven national parks and monuments are offering free admission on select dates this summer, including to the Grand Canyon and Yosemite.

The Park Service expects to lose $500,000 but hopes that there will be an increase in park tourism from last year.

This offer does not include charges for camping, reservations, tours and other expenses.

The dates are the weekends June 20-21, July 18-19 and Aug. 15-16.