At least 11,000 years ago
A Clovis point from this period was made from obsidian obtained at Obsidian Cliff.
10,000 years ago
Folsom people were in the Yellowstone area as early as 10,900 years ago—the date of an obsidian Folsom projectile point found near Pinedale, Wyoming. Sites all over the park yield paleoindian artifacts, particularly concentrated around Yellowstone Lake.
9,350 years ago
A site on the shore of Yellowstone Lake has been dated to 9,350 years ago. The points had traces of blood from rabbit, dog, deer, and bighorn sheep. People probably used this area in the summer while hunting bear, deer, bighorn, and rabbits, and perhaps making tools and clothes and seem to have occupied this site for short, seasonal periods.
8,000–1,500 years ago
Beginning 8,000 years ago until 1,500 common era (CE), people leave traces of camps on shores of Yellowstone Lake. Note: CE (Common Era) replaces AD.
7,000 years ago
Vegetation similar to what we find today begins to appear. Projectile points begin to be notched.
3,000 years ago
Oral histories of the Salish place their ancestors in the Yellowstone area. Artifacts dating to 3,000 years ago have also been discovered on islands in Yellowstone Lake, leading some archeologists to speculate that indigenous peoples used watercraft to travel there.
1,500 years ago
Bow and arrow begins to replace atlatl (throwing spear); sheep traps (in the mountains) and bison corrals (on the plains) begin to be used in the Rocky Mountain region.
Oral histories of the Kiowa place their ancestors in the Yellowstone area from this time through the 1700s.
Little Ice Age begins.
North American tribes in the southwest begin acquiring horses in the mid- to late 1600s. Ancestors of the Crow may have come into Yellowstone during this time.
Lakota Sioux begin exploring the Yellowstone area.
Late 1700s–1840s CE
Fur traders travel the rivers into the Yellowstone region. Tribes in the Yellowstone area begin using horses.
The Lewis and Clark Expedition passes within 50 miles of Yellowstone.
John Colter likely explores part of Yellowstone.
Trappers return to Yellowstone area.
Trapper Osborne Russell encounters Tukudika ("Sheep Eaters") in Lamar Valley.
Little Ice Age ends, climate begins to warm.
First organized expedition attempts but fails to explore the Yellowstone Plateau.
Gold strike northwest of Yellowstone.
Washburn–Langford–Doane Expedition; Old Faithful Geyser named.
First Hayden expedition.
Yellowstone National Park Protection Act establishes the first national park.
Nez Perce (Nee-me-poo) flee US Army through Yellowstone.
Northern Pacific Railroad reaches the north boundary of the park.
The US Army arrives to administer the park. They stay until 1918.
Poacher Ed Howell captured; National Park Protection Act (Lacey Act) passed.
President Theodore Roosevelt dedicates arch at the North Entrance by laying its cornerstone at Gardiner.
The Antiquities Act provides for the protection of historic, prehistoric, and scientific features on, and artifacts from, federal lands.
Union Pacific train service begins at West Yellowstone.
Private automobiles are officially admitted to the park.
The National Park Service Organic Act establishes the National Park Service.
US Army turns over park management to the National Park Service.
President Hoover signs first law changing park’s boundary.
President Hoover expands the park again (by executive order).
Civilian Conservation Corps established, works in Yellowstone through 1941.
The National Park Service Director’s Order prohibits killing predators.
The Historic Sites Act sets a national policy to “preserve for future public use historic sites, buildings, and objects.”
Yellowstone receives one million visitors.
Nineteen snowplane trips carry 49 passengers into the park in winter.
Mission 66 initiated. The first concession-run snowcoach trips carry more than 500 people into the park in winter.
Magnitude 7.5 M earthquake strikes on August 17 west of Yellowstone, killing campers in Gallatin National Forest and affecting infrastructure, and thermal areas in the park.
The Leopold Report is issued.
The thermophile Thermus aquaticus is discovered in a Yellowstone hot spring.
New bear management plan begins, which includes closing open-pit dumps in park.
Overnight winter lodging opens in park and continues yearly.
Grizzly bear listed as threatened species in the lower 48 states.
Public Law 100-443 protects hydrothermal features in national parks from geothermal development on adjacent federal lands; Summer of Fire: more than 790,000 acres affected by fires in Yellowstone.
Clean Air Act Amendments require air quality monitoring at sites including Yellowstone, a Class I airshed.
Congress enacts a law allowing a percentage of park entrance fees to be kept in the parks.
Wolves are restored to the park.
Federal buyout of gold mine on Yellowstone’s northeast border is authorized.
The National Parks Omnibus Management Act is passed.
Interagency Bison Management Plan is adopted by federal, state, and tribal partners.
National Academy of Sciences confirms effectiveness of Ecological Process Management (aka natural regulation).
Yellowstone's grizzly bears removed from federal threatened species list.
Scientific review panel recommends an increase in lake trout removal operations on Yellowstone Lake.
Grizzly bears returned to threatened species list. Bioprospecting final EIS completed; Science agenda established for Greater Yellowstone Ecosystem.
Grey wolves removed from the endangered species list in MT, ID, OR, and WA. Remain listed in WY until 2017.
National Park Service Centennial.
The Earliest Humans in Yellowstone
Human occupation of this area seems to follow environmental changes of the last 15,000 years.
European Americans Arrive
In the late 1700s, fur traders traveled the Yellowstone River in search of Native Americans with whom to trade.
Expeditions Explore Yellowstone
Formal expeditions mapped and explored the area, leading to the nation's understanding of the region.
Managing the national park has evolved over time and dealt with some complex issues.
Last updated: August 4, 2021