1822 – Charles Babbage proposes a difference engine in a paper to the Royal Astronomical Society.

1872 – Trade unions are legalized in Canada.

1937 – U.S. House of Representatives passes the Marihuana Tax Act.

1940 – Seven hundred and twenty-eight Polish political prisoners from Tarnów become the first inmates of the Auschwitz concentration camp.

1951 – UNIVAC I is dedicated by the U.S. Census Bureau.

1954 – U.S. President Dwight D. Eisenhower signs a bill into law that places the words "under God" into the United States Pledge of Allegiance.

1962 – The European Space Research Organisation is established in Paris – later becoming the European Space Agency.

2002 – Near-Earth asteroid 2002 MN misses the Earth by 75,000 miles (121,000 km), about one-third of the distance between the Earth and the Moon.

"Always has been"

1850 – The American League of Colored Laborers, the first African American labor union in the United States, is established in New York City.

1966 – The United States Supreme Court rules in Miranda v. Arizona that the police must inform suspects of their Fifth Amendment rights before questioning them (colloquially known as "Mirandizing").

1967 – U.S. President Lyndon B. Johnson nominates Solicitor-General Thurgood Marshall to become the first black justice on the U.S. Supreme Court.

1971 – Vietnam War: The New York Times begins publication of the Pentagon Papers.

1983 – Pioneer 10 becomes the first man-made object to leave the central Solar System when it passes beyond the orbit of Neptune.

1776 – The Virginia Declaration of Rights is adopted.

1817 – The earliest form of bicycle, the dandy horse, is driven by Karl von Drais.

1939 – The Baseball Hall of Fame opens in Cooperstown, New York.

1942 – Anne Frank receives a diary for her thirteenth birthday.

1963 – NAACP field secretary Medgar Evers is murdered in front of his home in Jackson, Mississippi, by Ku Klux Klan member Byron De La Beckwith during the civil rights movement.

1964 – Anti-apartheid activist and ANC leader Nelson Mandela is sentenced to life in prison for sabotage in South Africa.

1967 – The United States Supreme Court in Loving v. Virginia declares all U.S. state laws that prohibit interracial marriage to be unconstitutional.

1776 – The Continental Congress appoints Thomas Jefferson, John Adams, Benjamin Franklin, Roger Sherman, and Robert R. Livingston to the Committee of Five to draft a declaration of independence.

1936 – Inventor Edwin Armstrong demonstrates FM broadcasting to an audience of engineers at the FCC in Washington, DC.

1963 – American Civil Rights Movement: Governor of Alabama George Wallace defiantly stands at the door of Foster Auditorium at the University of Alabama in an attempt to block two black students, Vivian Malone and James Hood, from attending that school. Later in the day, accompanied by federalized National Guard troops, they are able to register.

1963 – John F. Kennedy addresses Americans from the Oval Office proposing the Civil Rights Act of 1964, which would revolutionize American society by guaranteeing equal access to public facilities, ending segregation in education, and guaranteeing federal protection for voting rights.

1692 – Salem witch trials: Bridget Bishop is hanged at Gallows Hill near Salem, Massachusetts, for "certaine Detestable Arts called Witchcraft and Sorceries".

1935 – Dr. Robert Smith takes his last drink, and Alcoholics Anonymous is founded in Akron, Ohio, United States, by him and Bill Wilson.

1944 – In baseball, 15-year-old Joe Nuxhall of the Cincinnati Reds becomes the youngest player ever in a major-league game.

2002 – The first direct electronic communication experiment between the nervous systems of two humans is carried out by Kevin Warwick in the United Kingdom.

1954 – Joseph N. Welch, special counsel for the United States Army, lashes out at Senator Joseph McCarthy during the Army–McCarthy hearings, giving McCarthy the famous rebuke, "You've done enough. Have you no sense of decency, sir, at long last? Have you left no sense of decency?"

1959 – The USS George Washington is launched. It is the first nuclear-powered ballistic missile submarine.

1968 – U.S. President Lyndon B. Johnson declares a national day of mourning following the assassination of Senator Robert F. Kennedy.

1949 – George Orwell's dystopian novel Nineteen Eighty-Four is published in the United States

1987 – New Zealand's Labour government establishes a national nuclear-free zone under the New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act 1987.

2023 – Former US President Donald Trump is indicted on federal charges of misusing classified information.

1776 – Richard Henry Lee presents the "Lee Resolution" to the Continental Congress. The motion is seconded by John Adams and will lead to the United States Declaration of Independence.

1892 – Homer Plessy is arrested for refusing to leave his seat in the "whites-only" car of a train; he lost the resulting court case, Plessy v. Ferguson.

1899 – American Temperance crusader Carrie Nation begins her campaign of vandalizing alcohol-serving establishments by destroying the inventory in a saloon in Kiowa, Kansas.

1938 – Second Sino-Japanese War: The Chinese Nationalist government creates the 1938 Yellow River flood to halt Japanese forces. Five hundred thousand to nine hundred thousand civilians are killed.

1965 – The Supreme Court of the United States hands down its decision in Griswold v. Connecticut, prohibiting the states from criminalizing the use of contraception by married couples.

1975 – Sony launches Betamax, the first videocassette recorder format.

1933 – The first drive-in theater opens in Camden, New Jersey.

1934 – New Deal: U.S. President Franklin D. Roosevelt signs the Securities Exchange Act of 1934 into law, establishing the U.S. Securities and Exchange Commission.

1942 – World War II: The United States Navy's victory over the Imperial Japanese Navy at the Battle of Midway is a major turning point in the Pacific Theater. All four Japanese fleet carriers taking part—Akagi, Kaga, Sōryū and Hiryū—are sunk, as is the heavy cruiser Mikuma. The American carrier Yorktown and the destroyer Hammann are also sunk.

1944 – World War II: Commencement of Operation Overlord: The Allied invasion of Normandy begins with the execution of Operation Neptune—commonly referred to as D-Day—the largest seaborne invasion in history. Nearly 160,000 Allied troops cross the English Channel with about 5,000 landing and assault craft, 289 escort vessels, and 277 minesweepers participating. By the end of the day, the Allies have landed on five invasion beaches and are pushing inland.

1851 – Harriet Beecher Stowe's anti-slavery serial, Uncle Tom's Cabin, or Life Among the Lowly, starts a ten-month run in the National Era abolitionist newspaper.

1916 – Louis Brandeis is sworn in as a Justice of the United States Supreme Court; he is the first American Jew to hold such a position.

1956 – Elvis Presley introduces his new single, "Hound Dog", on The Milton Berle Show, scandalizing the audience with his suggestive hip movements.

1968 – Presidential candidate Robert F. Kennedy is assassinated by Sirhan Sirhan.

1981 – The Morbidity and Mortality Weekly Report of the Centers for Disease Control and Prevention reports that five people in Los Angeles, California, have a rare form of pneumonia seen only in patients with weakened immune systems, in what turns out to be the first recognized cases of AIDS.

1989 – The Tank Man halts the progress of a column of advancing tanks for over half an hour after the Tiananmen Square protests of 1989.

2004 – Noël Mamère, Mayor of Bègles, celebrates marriage for two men for the first time in France.

2012 – Last transit of Venus until the year 2117.

1783 – The Montgolfier brothers publicly demonstrate their montgolfière (hot air balloon).

1912 – Massachusetts becomes the first state of the United States to set a minimum wage.

1939 – The Holocaust: The MS St. Louis, a ship carrying 973 German Jewish refugees, is denied permission to land in Florida, in the United States, after already being turned away from Cuba. Forced to return to Europe, more than 200 of its passengers later die in Nazi concentration camps.

1977 – JVC introduces its VHS videotape at the Consumer Electronics Show in Chicago. It will eventually prevail against Sony's rival Betamax system in a format war to become the predominant home video medium.

1989 – The 1989 Tiananmen Square protests are suppressed in Beijing by the People's Liberation Army, with between 241 and 10,000 dead (an unofficial estimate).

1844 – The last pair of great auks is killed.

1692 – Bridget Bishop is the first person to be tried for witchcraft in Salem, Massachusetts; she is found guilty the same day and hanged on June 10.

1966 – Surveyor program: Surveyor 1 lands in Oceanus Procellarum on the Moon, becoming the first U.S. spacecraft to soft-land on another world.

2003 – Europe launches its first voyage to another planet, Mars. The European Space Agency's Mars Express probe launches from the Baikonur space center in Kazakhstan.

193 – The Roman Senate passes a motion proclaiming Septimius Severus emperor, awards divine honours to Pertinax, and sentences current emperor Didius Julianus to death.

Marcus Didius Julianus (29 January 133 – 2 June 193) was Roman emperor from March to June 193, during the Year of the Five Emperors. He is known for having purchased the title of emperor in an auction run by the Praetorian Guard.

1494 – A monk, John Cor, records the first known batch of Scotch whisky.

1868 – The Treaty of Bosque Redondo is signed, allowing the Navajo to return to their lands in Arizona and New Mexico.

1974 – The Heimlich maneuver for rescuing choking victims is published in the journal Emergency Medicine.

1988 – The Intermediate-Range Nuclear Forces Treaty comes into effect.

1990 – Cold War: George H. W. Bush and Mikhail Gorbachev sign a treaty to end chemical weapon production.

 Red_Dragon wrote:

The Illustrated Story Behind the Tulsa Massacre (The Atlantic)

...from a recent Watchmen series (tv-show)

1909 – The National Negro Committee, forerunner to the National Association for the Advancement of Colored People (NAACP), convenes for the first time.

1921 – The Tulsa race massacre kills at least 39, but other estimates of black fatalities vary from 55 to about 300.

1941 – Anglo-Iraqi War: The United Kingdom completes the re-occupation of Iraq and returns 'Abd al-Ilah to power as regent for Faisal II.

1947 – Ferenc Nagy, the democratically elected Prime Minister of Hungary, resigns from office after blackmail from the Hungarian Communist Party accusing him of being part of a plot against the state. This grants the Communists effective control of the Hungarian government.

1955 – The U.S. Supreme Court expands on its Brown v. Board of Education decision by ordering district courts and school districts to enforce educational desegregation "at all deliberate speed."

2005 – Vanity Fair reveals that Mark Felt was "Deep Throat".

2010 – Israeli Shayetet 13 commandos board the Gaza Freedom Flotilla while still in international waters trying to break the ongoing blockade of the Gaza Strip; nine Turkish citizens on the flotilla were killed in the ensuing violent affray.

1806 – Future U.S. President Andrew Jackson kills Charles Dickinson in a duel.

1937 – Memorial Day massacre: Chicago police shoot and kill ten labor demonstrators.

1943 – The Holocaust: Josef Mengele becomes chief medical officer of the Zigeunerfamilienlager (Romani family camp) at Auschwitz concentration camp.

1975 – The European Space Agency is established.

1998 – Nuclear Testing: Pakistan conducts an underground test in the Kharan Desert. It is reported to be a plutonium device with yield of 20kt TNT equivalent.

2024 – Donald Trump is convicted of falsifying business records in his New York trial, the first time a former President of the United States has been found guilty in a criminal case.

"Ain't I a Woman?"

The leaders of the movement trembled on seeing a tall, gaunt black woman in a gray dress and white turban, surmounted with an uncouth sunbonnet, march deliberately into the church, walk with the air of a queen up the aisle, and take her seat upon the pulpit steps. A buzz of disapprobation was heard all over the house, and there fell on the listening ear, 'An abolition affair!" "Woman's rights and niggers!" "I told you so!" "Go it, darkey!" . .

(the speech went like)

"Wall, chilern, whar dar is so much racket dar must be somethin' out o' kilter. I tink dat 'twixt de niggers of de Souf and de womin at de Norf, all talkin' 'bout rights, de white men will be in a fix pretty soon. But what's all dis here talkin' 'bout?..

... Den dey talks 'bout dis ting in de head; what dis dey call it?" ("Intellect," whispered some one near.) "Dat's it, honey. What's dat got to do wid womin's rights or nigger's rights? If my cup won't hold but a pint, and yourn holds a quart, wouldn't ye be mean not to let me have my little half-measure full?" And she pointed her significant finger, and sent a keen glance at the minister who had made the argument. The cheering was long and loud.