Events
- 1751 - The first cricket match is played in America.
- 1778 - American Revolution: The Battle of Crooked Billet begins in Hatboro, Pennsylvania.
- 1785 - Kamehameha, the king of Hawaiʻi defeats Kalanikupule and establishes the Kingdom of Hawaiʻi
- 1846 - The few remaining Mormons left in Nauvoo, Illinois, formally dedicated the Nauvoo Temple.
- 1848 - The Fraternity of Phi Gamma Delta was founded at Jefferson College in Canonsburg, Pennsylvania.
- 1863 - American Civil War: The Battle of Chancellorsville begins.
- 1884 - Proclamation of the demand for eight-hour workday in the United States.
- 1886 - The start of the general strike which eventually wins the eight-hour workday in the United States. These events are today commemorated as May Day or Labour Day in most industrialized countries.
- 1893 - The World's Columbian Exposition opens in Chicago.
- 1894 - Coxey's Army, the first significant American protest march, arrives in Washington, D.C.
- 1898 - Spanish–American War: The Battle of Manila Bay - The United States Navy destroys the Spanish Pacific fleet in the first battle of the war.
- 1901 - The Pan-American Exposition opens in Buffalo, New York.
- 1915 - RMS Lusitania departs New York City on her two hundred and second and final crossing of the North Atlantic. Six days later, the ship was torpedoed off the coast of Ireland with the loss of 1,198 lives, including 128 Americans, rousing American sentiment against Germany.
- 1927 - The Union Labor Life Insurance Company is founded by the American Federation of Labor.
- 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 - Formation of western Indian state, Maharashtra.
- 1960 - Cold War: U-2 Crisis – Francis Gary Powers, in a Lockheed U-2 spyplane, is shot down over the Soviet Union, sparking off a diplomatic crisis.
- 1970 - Protests erupt in Seattle, following the announcement by U.S. President Richard Nixon that U.S. Forces in Vietnam would pursue enemy troops into Cambodia, a neutral country.
- 1971 - Amtrak (the National Railroad Passenger Corporation) is formed to take over U.S. passenger rail service.
- 1978 - The first unsolicited bulk commercial e-mail (which would later become known as "spam") is sent by a DEC marketing representative to every ARPANET address on the west coast of the United States.
- 1982 - The 1982 World's Fair opens in Knoxville, Tennessee.
- 1989 - Disney-MGM Studios opens at Walt Disney World near Orlando, Florida, United States.
- 1991 - Rickey Henderson would steal his 939th base, making him the all-time leader in this category. However, his accomplishment would be overshadowed later that evening by Nolan Ryan, who would pitch his seventh career no-hitter (breaking his own record).
- 1992 - On the third day of the 1992 Los Angeles riots, African American activist and criminal Rodney King appeared in public before television news cameras to appeal for calm and plead for peace, asking, "People, I just want to say, you know, can we all get along?".
- 2003 - 2003 invasion of Iraq: In what becomes known as the "Mission Accomplished speech", U.S. President George W. Bush declares "major combat operations in Iraq have ended" on board USS Abraham Lincoln off the coast of California.
- 2007 - The Los Angeles May Day mêlée occurred, in which the Los Angeles Police Department response to a May Day pro-immigration rally became a matter of controversy.