Ballard, Boyle, Crittenden, Letcher and Marshall counties are formed.
U.S. & World
U.S. Army Lieutenant John Charles Fremont maps out the Oregon Trail, opening the west to wagon trains.
The Supreme Court rules that slave-owners may do anything to recapture fugitives, but that state officials are not obliged to help track runaways. This interpretation will become obsolete in 1850, when Henry Clay proposes a new fugitive slave law that will incorporate direct federal involvement.