1846 – The few remaining Mormons left in Nauvoo, Illinois, formally dedicate the Nauvoo Temple.
1862 – American Civil War: The Union Army completes its capture of New Orleans.
1866 – The Memphis Race Riots begin. Reports of the riots influenced the passage of the Fourteenth Amendment.
1884 – Moses Fleetwood Walker becomes the first black person to play in a professional baseball game in the United States.
1886 – Rallies are held throughout the United States demanding the eight-hour workday, culminating in the Haymarket affair in Chicago, in commemoration of which May 1 is celebrated as International Worker’s Day.
1900 – The Scofield Mine disaster kills over 200 men in Scofield, Utah in what is to date the fifth-worst mining accident in U.S. history.
1931 – The Empire State Building is dedicated in New York City.
1950 – Guam is organized as a United States commonwealth.
1956 – The polio vaccine developed by Jonas Salk is made available to the public.
1960 – Francis Gary Powers, in a Lockheed U-2 spy plane, is shot down over the Soviet Union, sparking a diplomatic crisis.
1999 – SpongeBob SquarePants premieres on Nickelodeon.
2003 – In what became known as the “Mission Accomplished” speech, on board the USS Abraham Lincoln, President George W. Bush declares that “major combat operations in Iraq have ended.”
2011 – President Barack Obama announced that Osama bin Laden was killed in a U.S. commando raid on his compound near the Pakistani capital.
