1775 – American Revolutionary War: The Siege of Boston begins, following the battles at Lexington and Concord.
1789 – George Washington arrives at Grays Ferry, Philadelphia while en route to Manhattan for his inauguration
1818 – The case of Ashford v Thornton ends, with Abraham Thornton allowed to go free rather than face a retrial for murder, after his demand for trial by battle is upheld.
1836 – U.S. Congress passes an act creating the Wisconsin Territory.
1850 – Daniel Chester French, American sculptor, designed the Lincoln statue (d. 1931) is born.
1861 – American Civil War: Robert E. Lee resigns his commission in the United States Army in order to command the forces of the state of Virginia.
1862 – Louis Pasteur and Claude Bernard complete the experiment falsifying the theory of spontaneous generation.
1871 – The Civil Rights Act of 1871 becomes law.
1912 – Opening day for baseball's Tiger Stadium in Detroit, and Fenway Park in Boston.
1914 – Nineteen men, women, and children die in the Ludlow Massacre during a Colorado coal-miner's strike.
1916 – The Chicago Cubs play their first game at Weeghman Park (currently Wrigley Field), defeating the Cincinnati Reds 7–6 in 11 innings.
1918 – Manfred von Richthofen, a.k.a. The Red Baron, shoots down his 79th and 80th victims, his final victories before his death the following day.
1941 – Ryan O'Neal, American actor is born.
1945 – Steve Spurrier, American football player and coach is born.
1951 – Luther Vandross, American singer-songwriter and producer (d. 2005) is born.
1961 – Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba.
1966 – David Filo, American businessman, co-founded Yahoo! is born.
1972 – Apollo 16, commanded by John Young, lands on the moon.
1999 – Columbine High School massacre: Eric Harris and Dylan Klebold killed 13 people and injured 24 others before committing suicide at Columbine High School in Columbine, Colorado.
2007 – Johnson Space Center shooting: William Phillips with a handgun barricades himself in NASA's Johnson Space Center in Houston, Texas before killing a male hostage and himself.
2008 – Danica Patrick wins the Indy Japan 300 becoming the first female driver in history to win an Indy car race.
2010 – The Deepwater Horizon drilling rig explodes in the Gulf of Mexico, killing eleven workers and beginning an oil spill that would last six months.
2016 – Chyna, American wrestler (b. 1969) dies.