A big horn sheep is seen reflected in rearview mirror down an empty road at Badlands National Park as the spread of the coronavirus disease (COVID-19) continues, where visitors centers and entrance stations are closed but roads, campgrounds and trails remain open near Wall, South Dakota, U.S., April 16, 2020. REUTERS/Shannon Stapleton 

An empty staircase leads to a vista point at Badlands National Park as the spread of the coronavirus disease (COVID-19) continues, where their are closed visitor centers, suspended interpretive programs yet campgrounds and trails remain open near Wall, South Dakota, U.S., April 16, 2020. REUTERS/Shannon Stapleton 

People walk at a scenic viewpoint area at Badlands National Park as the spread of the coronavirus disease (COVID-19) continues, where visitors centers and entrance stations are closed but roads, campgrounds and trails remain open near Wall, South Dakota, U.S., April 16, 2020. REUTERS/Shannon Stapleton 

A view of the Badlands National Park is seen near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

A sing reads "end of trail" in the Badlands National Park near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

Tourists visit the Badlands National Park near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

A view of the Badlands National Park is seen near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

Tourists visit the Badlands National Park near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

A view of the Badlands National Park is seen near Interior, South Dakota, U.S., November 8, 2019. REUTERS/Stephanie Keith 

Fort Laramie treaty riders approach the lunch camp along the Sage Creek Road in the Badlands National Park outside of Wall, South Dakota, U.S., April 19, 2018. REUTERS/Stephanie Keith 

Fort Laramie treaty riders approach the lunch camp along the Sage Creek Road in the Badlands National Park outside of Wall, South Dakota, U.S., April 19, 2018. REUTERS/Stephanie Keith 

A small herd of Buffalo run past horse trailer used by Fort Laramie treaty riders along the Sage Creek Road in the Badlands National Park outside of Wall, South Dakota, U.S., April 19, 2018. REUTERS/Stephanie Keith 

Fort Laramie treaty riders ride along the Sage Creek Road in the Badlands National Park outside of Wall, South Dakota, U.S., April 19, 2018. REUTERS/Stephanie Keith 

A small herd of buffalo grazes near the Sage Creek campground in the Badlands National Park outside of Wall, South Dakota, U.S., April 19, 2018. REUTERS/Stephanie Keith SEARCH "KEITH ANNIVERSARY" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. 

Jessie James White, one of the Fort Laramie treaty riders, sets out in the morning from the Rockyford School towards the Badlands National Park in the Pine Ridge Reservation in Rockyford, South Dakota, U.S., April 21, 2018. REUTERS/Stephanie Keith 

The Fort Laramie treaty riders set out in the morning from the Rockyford School towards the Badlands National Park in the Pine Ridge Reservation in Rockyford, South Dakota, U.S., April 21, 2018. REUTERS/Stephanie Keith 

The chasm of the Grand Canyon is pictured in Arizona June 23, 2013. Daredevil Nik Wallenda completed a historic high-wire walk over a section of the Grand Canyon on Sunday, greeted with wild cheers after finishing his journey over the yawning chasm on a 2-inch (5-cm) steel cable. REUTERS/Mike Blake (UNITED STATES - Tags: SOCIETY ENVIRONMENT TRAVEL)