1812 Louisiana became the 18th state, albeit one with an obviously much decreased territorial expanse compared to the territory it represented when sold to the United States.
1869 Union Pacific reached Promontory Point, Utah.
1906 A and B Mines opened at Superior.
1926 The cornerstone was laid for the University of Wyoming's engineering building. Attribution: On This Day. The photo above depicts the building some time in the 1950s. The one below, in 1986.