1854 – American Transcendentalist philosopher Henry David Thoreau publishes his memoir Walden.

1944 – The United States Forest Service and the Wartime Advertising Council release posters featuring Smokey Bear for the first time.

1945 – World War II: Nagasaki is devastated when an atomic bomb, Fat Man, is dropped by the United States B-29 Bockscar. Thirty-five thousand people are killed outright, including 23,200–28,200 Japanese war workers, 2,000 Korean forced workers, and 150 Japanese soldiers.

1974 – As a direct result of the Watergate scandal, Richard Nixon becomes the first president of the United States to resign from office. Vice President Gerald Ford becomes president.

1995 - The Dateless Day

1576 – The cornerstone for Tycho Brahe's Uraniborg observatory is laid on the island of Hven.

1969 – At a zebra crossing in London, photographer Iain Macmillan takes the iconic photo that becomes the cover image of the Beatles' album Abbey Road.

1974 – President Richard Nixon, in a nationwide television address, announces his resignation from the office of the President of the United States effective noon the next day.

1988 – The first night baseball game in the history of Chicago's Wrigley Field (game was rained out in the fourth inning).

2004 – A tour bus belonging to the Dave Matthews Band dumps approximately 800 pounds of human waste onto a boat full of passengers.

1944 – IBM dedicates the first program-controlled calculator, the Automatic Sequence Controlled Calculator (known best as the Harvard Mark I).

1787 – Sixty proof sheets of the Constitution of the United States are delivered to the Constitutional Convention in Philadelphia, Pennsylvania.

1901 – Kiowa land in Oklahoma is opened for white settlement, effectively dissolving the contiguous reservation.

1926 – First public screening using the Vitaphone process.

1945 – World War II: Hiroshima, Japan is devastated when the atomic bomb "Little Boy" is dropped by the United States B-29 Enola Gay. Around 70,000 people are killed instantly, and some tens of thousands die in subsequent years from burns and radiation poisoning.

1965 – US President Lyndon B. Johnson signs the Voting Rights Act of 1965 into law.

1991 – Tim Berners-Lee releases files describing his idea for the World Wide Web. WWW makes its first appearance as a publicly available service on the Internet.

1996 – NASA announces that the ALH 84001 meteorite, thought to originate from Mars, contains evidence of primitive life-forms.

2012 – NASA's Curiosity rover lands on the surface of Mars.

US air traffic control strike

1861 – American Civil War: In order to help pay for the war effort, the United States government levies the first income tax as part of the Revenue Act of 1861 (3% of all incomes over US$800; rescinded in 1872).

1914 – In Cleveland, Ohio, the first electric traffic light is installed.

1925 – Plaid Cymru is formed with the aim of disseminating knowledge of the Welsh language that is at the time in danger of dying out.

1957 – American Bandstand, a show dedicated to the teenage "baby-boomers" by playing the songs and showing popular dances of the time, debuts on the ABC television network.

1962 – American actress Marilyn Monroe is found dead at her home from a drug overdose.

1963 – Cold War: The United States, the United Kingdom, and the Soviet Union sign the Partial Nuclear Test Ban Treaty.

1974 – Watergate scandal: President Richard Nixon, under orders of the US Supreme Court, releases the "Smoking Gun" tape, recorded on June 23, 1972, clearly revealing his actions in covering up and interfering investigations into the break-in. His political support vanishes completely.

1889 – The Great Fire of Spokane, Washington destroys some 32 blocks of the city, prompting a mass rebuilding project.

1944 – The Holocaust: A tip from a Dutch informer leads the Gestapo to a sealed-off area in an Amsterdam warehouse, where they find and arrest Jewish diarist Anne Frank, her family, and four others.

1977 – U.S. President Jimmy Carter signs legislation creating the United States Department of Energy.

1987 – The Federal Communications Commission rescinds the Fairness Doctrine which had required radio and television stations to give equal time to opposing views.

1992 -  The American revisionist western Unforgiven had its world premiere, and it later won four Academy Awards, including best director for Clint Eastwood, who also starred in the drama, and best picture.

1778 – The theatre La Scala in Milan is inaugurated with the première of Antonio Salieri's Europa riconosciuta.

1977 – Tandy Corporation announces the TRS-80, one of the world's first mass-produced personal computers.

1776 – American Revolution: The signing of the United States Declaration of Independence by the Second Continental Congress takes place.

1934 – Reichskanzler Adolf Hitler becomes Führer of Germany following the death of President Paul von Hindenburg.

1937 – The Marihuana Tax Act of 1937 is passed in America, the effect of which is to render marijuana and all its by-products illegal.

1939 – Albert Einstein and Leo Szilard write a letter to Franklin D. Roosevelt, urging him to begin the Manhattan Project to develop a nuclear weapon.

1800 – The Acts of Union 1800 are passed which merge the Kingdom of Great Britain and the Kingdom of Ireland into the United Kingdom of Great Britain and Ireland.

1834 – Slavery is abolished in the British Empire as the Slavery Abolition Act 1833 comes into force, although it remains legal in the possessions of the East India Company until the passage of the Indian Slavery Act, 1843.

1933 – Anti-Fascist activists Bruno Tesch, Walter Möller, Karl Wolff and August Lütgens are executed by the Nazi regime in Altona.

1965 – Frank Herbert's novel, Dune, is published for the first time. It was named as the world's best-selling science fiction novel in 2003.

1971 – The Concert for Bangladesh, organized by former Beatle George Harrison, is held at Madison Square Garden in New York City.

1980 – Vigdís Finnbogadóttir is elected President of Iceland and becomes the world's first democratically elected female head of state.

1981 – MTV begins broadcasting in the United States and airs its first video, "Video Killed the Radio Star" by The Buggles.

2023 – Former US President Donald Trump is indicted for his role in the January 6 United States Capitol attack, his third indictment in 2023.

1932 – The NSDAP (Nazi Party) wins more than 38% of the vote in German elections.

1941 – The Holocaust: Under instructions from Adolf Hitler, Nazi official Hermann Göring orders SS General Reinhard Heydrich to "submit to me as soon as possible a general plan of the administrative material and financial measures necessary for carrying out the desired Final Solution of the Jewish question."

1964 – Ranger program: Ranger 7 sends back the first close-up photographs of the moon, with images 1,000 times clearer than anything ever seen from earth-bound telescopes.

1991 – The United States and Soviet Union both sign the START I Strategic Arms Reduction Treaty, the first to reduce (with verification) both countries' stockpiles.

2007 – Operation Banner, the presence of the British Army in Northern Ireland, and the longest-running British Army operation ever, comes to an end.

1619 – In Jamestown, Virginia, the first Colonial European representative assembly in the Americas, the Virginia General Assembly, convenes for the first time.

1956 – A joint resolution of the U.S. Congress is signed by President Dwight D. Eisenhower, authorizing In God We Trust as the U.S. national motto.

1965 – U.S. president Lyndon B. Johnson signs the Social Security Act of 1965 into law, establishing Medicare and Medicaid.

1974 – Watergate scandal: U.S. President Richard Nixon releases subpoenaed White House recordings after being ordered to do so by the Supreme Court of the United States.

2003 – Three years after the death of the last Pyrenean ibex, Celia, a clone of her is born only to subsequently die from lung defects. Within minutes, the Pyrenean ibex becomes the first and so far only species to have ever gone de-extinct as well as go extinct twice.

1921 – Adolf Hitler becomes leader of the National Socialist German Workers' Party.

1957 – Tonight Starring Jack Paar premieres on NBC with Jack Paar beginning the modern day talk show.

1868 – The 14th Amendment to the United States Constitution is certified, establishing African American citizenship and guaranteeing due process of law.

1973 – Summer Jam at Watkins Glen: Nearly 600,000 people attend a rock festival at the Watkins Glen International Raceway.

1789 – The first U.S. federal government agency, the Department of Foreign Affairs, is established (it will be later renamed Department of State).

1794 – French Revolution: Maximilien Robespierre is arrested after encouraging the execution of more than 17,000 "enemies of the Revolution".

1866 – The first permanent transatlantic telegraph cable is successfully completed, stretching from Valentia Island, Ireland, to Heart's Content, Newfoundland.

1890 – Vincent van Gogh shoots himself and dies two days later.

1921 – Researchers at the University of Toronto, led by biochemist Frederick Banting, prove that the hormone insulin regulates blood sugar.

1940 – The animated short A Wild Hare is released, introducing the character of Bugs Bunny.

1184 – Erfurt latrine disaster: At a Hoftag, a meeting with local notables, organized by Henry VI, the building collapses and many of the nobles in attendance drown in the sewage pits below.

1882 – Premiere of Richard Wagner's opera Parsifal at Bayreuth.

1948 – U.S. president Harry S. Truman signs Executive Order 9981, desegregating the military of the United States.

1989 – A federal grand jury indicts Cornell University student Robert T. Morris, Jr. for releasing the Morris worm, thus becoming the first person to be prosecuted under the 1986 Computer Fraud and Abuse Act.

2016 – Hillary Clinton becomes the first female nominee for president of the United States by a major political party at the Democratic National Convention in Philadelphia.

1934 – The Nazis assassinate Austrian Chancellor Engelbert Dollfuss in a failed coup attempt.

1965 – Bob Dylan goes electric at the Newport Folk Festival, signaling a major change in folk and rock music.

1976 – Viking program: Viking 1 takes the famous Face on Mars photo.

1978 – Birth of Louise Joy Brown, the first human to have been born after conception by in vitro fertilisation, or IVF.

2010 – WikiLeaks publishes classified documents about the War in Afghanistan, one of the largest leaks in U.S. military history.

1974 – Watergate scandal: The United States Supreme Court unanimously ruled that President Richard Nixon did not have the authority to withhold subpoenaed White House tapes and they order him to surrender the tapes to the Watergate special prosecutor.