1782 Gnadenhütten massacre: Ninety-six Native Americans in Gnadenhutten, Ohio, who had converted to Christianity are killed by Pennsylvania militiamen in retaliation for raids carried out by other Indians.
1803 Ohio is admitted as the 17th U.S. state.
1925 USS ''Shenandoah'' (ZR-1), the United States' first American-built rigid airship, was destroyed in a squall line over Noble County, Ohio. Fourteen of her 42-man crew perished, including her commander, Zachary Lansdowne.
1953 Frances Bolton and her son, Oliver from Ohio, become the first mother and son to serve simultaneously in the U.S. Congress.
1970 Vietnam War: Kent State shootings: the Ohio National Guard, sent to Kent State University after disturbances in the city of Kent the weekend before, open fire killing four students and wounding nine others. The students were protesting the United States' invasion of Cambodia.
1971 Ohio ratifies the 26th Amendment to the U.S. Constitution, lowering the voting age to 18, thereby putting the amendment into effect.
1990 The Lower Ohio Valley tornado outbreak spawns 66 confirmed tornadoes in Illinois, Indiana, Kentucky, and Ohio, killing 12. Petersburg, Indiana, is the hardest-hit town in the outbreak, with 6 deaths.
1993 450 prisoners rioted at the Southern Ohio Correctional Facility in Lucasville, Ohio, and continued to do so for ten days, citing grievances related to prison conditions, as well as the forced vaccination of Nation of Islam prisoners (for tuberculosis) against their religious beliefs.