1848 Mexico ratifies the Treaty of Guadalupe Hidalgo acknowledging the acquisition of Texas and New Mexico by the United States, which included a small portion of Wyoming, via Texas.
1846 resident Polk approved an act that provided for a line of military posts along the Oregon Trail. In some ways, this has to be regarded as a major development in the history of the United States and the U.S. Army, as the expansion of the Army on to the Western Frontier dominated much of its character for the next century, even continuing to have an influence into its nature well after the Frontier had closed. Attribution: On This Day.
1866 Colonel Carrington left Fort Kearny for Fort Laramie where he received instructions from General Pope to name two new outpost along Bozeman Road Fort Philip Kearny and Fort C.F. Smith. The widely spaced forts were to form more northerly bastions to guard the Bozeman Trail, the southernmost post, Ft. Reno, having already been established during the Civil War by Patrick Connor. Carrington was one of a group of officers who remained in the Army following the Civil War when Congress established the policy of making room for some wartime officers who had not come from pre war military service or West Point. Alfred Terry was another, with both men having been lawyers prior to the Civil War. Attribution: On This Day.
1869 Territorial government was formally in effect. Territorial Supreme Court took the oath of office.
1871 Robert H. Milroy takes office as U.S. Marshall.
1887 Sheridan Post established.
1902 The first Carnegie Library in the United States, the Laramie County Library, opened. Attribution: Wyoming State Historical Society.
1915 Dr. Amos Barber, Wyoming's second governor after statehood, whose governorship was marred by the Johnson County War and his general ineffective reaction to it, died. Barber had a successful career as an Army surgeon before entering private practice, and he followed up on that with service again during the Spanish American War, but his having participated through acts of omission in the large cattleman's invasion of central Wyoming is principally what he is remembered for.
1938 Niobrara County Wyoming becomes the first county in the United States to have all of its mail for a day delivered via airmail. Attribution: Wyoming State Historical Society.
1941 Fire destroyed three Union Pacific shop buildings in Cheyenne. Attribution: Wyoming State Historical Society.
1987 The U.S. Post Office in Basin Wyoming, the U.S. Post Office in Buffalo the U.S. Post Office in Evanston, the U.S. Post Office and Federal Courthouse in Lander, the U.S. Post Office in Yellowstone National Park, the U.S. Post Office in Newcastle, the U.S. Post Office in Kemmerer, the U.S. Post Office in Thermopolis, the U.S. Post Office in Torrington, added to the National Register of Historic Places.
1996 A 4.2 magnitude earthquake, which your correspondent experienced, occurred 22 miles from Casper.