The National Park Service claims money is badly needed for infrastructure
Several national parks in the United States are proposing to double their entrance fee for members of the general public.
Under the proposal from the National Park Service (NPS), peak-season fees would be established at 17 parks.
It would see an entrance fee of US$70 (€59) for a private car, US$50 (€42) for a motorbike and US$30 (€25) per person.
While a number of parks already charge for admission, these new fees are almost double some of the existing ones.
For example at Arches National Park in Utah, the current entry fee per person is US$10 (€8) - under these proposals, this would increase to US$30 (€25).
The NPS says the fees would "generate badly needed revenue for improvements to the aging infrastructure of national parks."
This includes roads, bridges bathrooms and other services.
US Secretary of the Interior, Ryan Zinke, said: "The infrastructure of our national parks is aging and in need of renovation and restoration.
"Targeted fee increases at some of our most-visited parks will help ensure that they are protected and preserved in perpetuity and that visitors enjoy a world-class experience that mirrors the amazing destinations they are visiting."
The proposed new structure would be implemented at Arches, Bryce Canyon, Canyonlands, Denali, Glacier, Grand Canyon, Grand Teton, Olympic, Sequoia & Kings Canyon, Yellowstone, Yosemite, and Zion National Parks from May 1st, 2018.
A number of other places - Acadia, Mount Rainier, Rocky Mountain, Shenandoah and Joshua Tree National Parks - are also on the list for later next year.