As the National Park Service celebrates 100 years, a photographer says Yellowstone National Park is succeeding at preserving its wild landscape.

Bradly Boner spent three summers in Yellowstone re-photographing more than a hundred photos taken in 1871. The original shots are from a survey expedition to what would become Yellowstone National Park. And Boner says nearly a century and a half later, the landscape remains remarkably intact.

“Most of the changes that you see today are the intrusions of human beings upon the landscape—roads, bridges, you can see some buildings in the photographs at Mammoth.” But, Boner said, “those are the kind of things that are the inevitable sacrifices that allow millions of people to experience Yellowstone every year.”

He says lining up his camera with William Henry Jackson’s original photos was like looking through a window into the past. “There are some of these photographs where individual rocks, individual trees are still there today. I was very surprised to see rocks the size of a bowling ball in the exact spot that they were when Jackson photographed that scene.”

Boner says the photos show the value of the National Park system. “It was very eye opening for me to see how nature can carry on if we just leave it alone.” 

The then-and-now photographs are on display at the National Museum of Wildlife Art in Jackson until late August. Boner will be at the museum for a public reception on Thursday, July 28.