- 18,000 B.C. Earliest evidence of humans in Wyoming.
- A.D. 1807 John Colter explores the Yellowstone area, coming as far south as Jackson Hole.
- 1812 Fur trader Robert Stuart discovers South Pass, the gentlest route across the northern Rockies.
- 1843 Pioneers begin traveling west on the Oregon Trail through Wyoming.
- 1848 The U.S. Army moves into Fort Laramie to protect Oregon Trail travelers from Indians.
- 1852 The first school in the state is founded at Fort Laramie.
- 1860 The Pony Express begins its run from Missouri to California, through Wyoming.
- 1867 The Union Pacific Railroad enters Wyoming.
- 1868 The Treaty of Fort Bridger creates the Shoshone Reservation in northwest Wyoming.
- 1868 The Territory of Wyoming is created by Congress.
- 1869 Wyoming Territorial Legislature grants women the right to vote and hold elective office.
- 1870 Esther H. Morris becomes the nation's first female justice of the peace.
- 1872 Yellowstone National Park is established as the nation's first national park.
- 1884 First oil well is drilled in Wyoming.
- 1886-87 Great blizzard decimates ranches of eastern Wyoming, sending many cattle barons into bankruptcy.
- 1889 The state constitution is adopted.
- 1890 Wyoming becomes the nation's 44th state.
- 1892 The Johnson County War breaks out over a dispute about cattle rustling.
- 1897 The first Cheyenne Frontier Days rodeo is staged.
- 1906 Devils Tower is established by President Theodore Roosevelt as the country's first national monument.
- 1910 Buffalo Bill Dam is completed.
- 1925 Nellie Taylor Ross becomes the nation's first female governor.
- 1927 Man claiming to be Butch Cassidy visits Wyoming from Washington, suggesting that the outlaw was not killed in Bolivia as was generally believed.
- 1929 Grand Teton National Park is established, consisting of only the peaks.
- 1929 Oil thefts discovered on federal land at Teapot Dome, a scandal that rocks the Harding Administration.
- 1950 National forest and private lands are added to form Grand Teton National Park as it is today.
- 1965 Minuteman missile sites are completed near Cheyenne.
- 1973 The Arab oil embargo sends oil prices skyrocketing, instigating a huge oil-drilling boom in Wyoming.
- 1988 Five fires break out around Yellowstone National Park, blackening approximately one-third of the park.
- 1996 The National Park Service institutes a voluntary ban on climbing Devils Tower during June to respect American Indian religious ceremonies.
- 1998 Gay University of Wyoming student Matthew Shepard murdered.
- 2002 The $10-million National Historic Trails Center opens in Casper.
- 2004 The state enjoys a nearly $1-billion surplus in its annual budget, thanks to increased drilling and mining activity.
- 2006 The famed tram at Jackson Hole Mountain Resort closes.
- 2008 The tram reopens in time for the ski season.