The following events affected political boundaries, record keeping, and family movements.

1834	Fort Laramie was established as a supply depot on the Oregon Trail fur trade route. It became an army post in 1849, and remained in use until 1890.
1840s-1850s	Emigrants went west over the Oregon Trail through what is now central Wyoming. In 1850, more than 40,000 emigrants passed through Fort Laramie.
1843	Fort Bridger was established.
1861-1868	The Dakota Territory was established. It included all of present-day North and South Dakota and most of Montana and Wyoming. In 1867 all of the Wyoming portion was included in Laramie County, which was divided early in 1868 by the creation of Carter County (later renamed Sweetwater County).
1867-1869	The transcontinental Union Pacific Railway was built through southern Wyoming. The towns of Cheyenne, Laramie, Rawlins, Rock Springs, Green River, and Evanston sprang up along its route.
1868	Wyoming Territory was created, primarily from Dakota Territory. It included small portions from Utah and Idaho territories.
1876-1880s	The Arapaho and Cheyenne Indians were moved to the Wind River Reservation. With the defeat of the Sioux soon afterward, northern Wyoming was opened to cattle grazing. The cattle boom reached its height in the 1880s.
1890	Wyoming became a state.
1895-1910	The Carey Act of 1894 provided for the reclamation and homesteading of desert land, and stimulated new settlements in northern Wyoming. Mormons established towns in the Big Horn Basin.