1803: The US buys the Louisiana territories, which includes Wyoming.

1805: Lewis and Clark explore much of Montana along the Missouri, Marias, and Yellowstone Rivers.

1840-1860's: Settlers on the Oregon and Mormon Trails cross through Wyoming.

1849: U.S. military forces establish Fort Laramie as a major staging ground and supply post along the Oregon and Mormon Trails. Major military campaigns against the region's Indians are staged here.

1867-1868: The Union Pacific Railroad reaches the settlement of Cheyenne, which is made capital of the Wyoming Territory. The railroad further enabled the establishment of Laramie and Rock Springs.

1868: After many skirmishes between White settlers and Indians, the second Treaty of Fort Laramie is signed closing settlement of Powder River Country. This treaty would be repeatedly violated and resulted in the Black Hills War in 1876 which resulted in the U.S. Government's acquisition of the Black Hills.

1868: Wyoming Territory is established.

1869: Cheyenne, Wyoming becomes the first location in America in which women are given the right to vote.

1872: Wyoming's Yellowstone Park becomes the nation's first national park.

1890: Wyoming is admitted as the 44th state.

1891: Wyoming's Shoshone Forest becomes the nation's first National Forest.

1892: An armed war breaks out between small farmers and wealthy ranchers over land and water rights in what came to be known as the Johnson County War. Dozens of people were killed (some by hired mercenaries) and the events of the war, in part, gave rise to the idea of the "Wild West."

1906: Wyoming's Devils Tower becomes the nation's first national monument.

1921: Teapot Dome oil scandal rocks the presidency of Warren G. Harding