American historians are still arguing about the route taken by John Colter in the Mountain States in the early 19th century.

The trapper from Virginia left Camp Dubois on the Mississippi with about 40 other adventurers in mid-May 1804 to explore the west of the country on President Jefferson's orders.

The Lewis and Clark Expedition, the first overland expedition to the Pacific, took Colter and his companions from modern-day Illinois to the Great Plains, the Rocky Mountains, and through the Northwest before seeing the ocean in late 1805.

On the way back east, Colter parted from the expedition in the summer of 1806.

The experienced hunter and trapper wanted to travel to the Yellowstone River, a tributary of the Missouri, with two other trappers.

There the records become fragmentary.

Colter is said to have canoed down the river alone at the time, was recruited by the Missouri Fur Company, and helped build Fort Raymond on the Bighorn River in what is now Montana.

The man with a 30-pound backpack

As the politician and writer Henry Brackenridge later reconstructed, Colter set out again in the fall of 1807 to recruit Native American tribes as potential trading partners.

"This man, with a 30-pound backpack, his gun and ammunition, traveled 500 miles to the Crows, gave them information, and then set out for other tribes," wrote Brackenridge.

The path that Colter traveled back then continues to fascinate historians.

Did she guide the trapper through present-day Cody, the Absaroka range of hills, or Teton Pass?

On the other hand, the researchers agree on Colter's role in exploring the American West.

The trapper from Virginia, who had already made it to the Pacific with Jefferson's former private secretary Meriwether Lewis and William Clark, is considered the first American of European origin to set foot in what is now Yellowstone National Park in the winter of 1807/1808.

Upon returning to Fort Raymond, he described the region on Wyoming's Montana-Idaho border as a mysterious area of ​​"boiling mud," "fountains of water," and "steam from the earth."

A good 60 years later, on March 1, 1872, Congress declared the area with the geysers and hot springs described by Colter to be Yellowstone, the first national park in the United States.

The "public park or amusement park for the benefit and enjoyment of the people," as stated in the founding charter at the time, attracts around four million visitors every year.

In addition to geothermal features such as the world's largest number of active geysers, lakes, mountain ranges and sprawling plains reminiscent of lunar landscapes, Yellowstone is known for herds of bison, elk and grizzlies.

The Grand Loop takes visitors nearly 140 miles past Old Faithful, a jet-shaped geyser, Yellowstone's Grand Canyon, and Mammoth Hot Springs, travertines with waters reaching 70 degrees.

On the occasion of the 150th anniversary, Park Warden Cameron Sholly recalled the less than creditable beginnings in Yellowstone.

In order to make the national park safe for visitors, the Ministry of the Interior, as the supervisory authority for the approximately 9,000 square kilometer area, had systematically released predators, including bears and wolves, for shooting.

"We were interfering with the ecosystem and throwing it off balance," Sholly said.

The darker chapters also include dealing with Native Americans: After more than 11,000 years, during which tribes such as Shoshonen, Kiowa and Blackfeet had hunted in Yellowstone's forests and mountains, they were pushed out of the region after the establishment of the national park and with the help of soldiers been prevented from returning.

Visitors were told Yellowstone was never inhabited by indigenous people.

They would have avoided the "burning mountains" because of the geysers.

For several months now, the park administration has been working with representatives of various tribes to tell the story of the Yellowstone Indians in a "Tribal Heritage Center".

On the occasion of the 150th anniversary, a camp made of tipis is also planned for August, where visitors can exchange ideas with Indians.

"In the future, we're trying to show the history of the different tribes in Yellowstone," Sholly said.

"And no one can do that better than her."