September - 1969

• September 1 – A coup in Libya ousts King Idris, and brings Colonel Muammar Gaddafi to power.
• September 2
  • The first automatic teller machine in the United States is installed in Rockville Centre, New York.
  • Ho Chi Minh, former president of the Democratic Republic of Vietnam, dies.
• September 5 – Lieutenant William Calley is charged with 6 counts of premeditated murder, for the 1968 My Lai Massacre deaths of 109 Vietnamese civilians in My Lai, Vietnam.
• September 9 – Allegheny Airlines Flight 853 DC-9 collides in flight with a Piper PA-28, and crashes near Fairland, Indiana, killing all 83 persons in both aircraft.
• September 13 – The long-running animated franchise, Scooby-Doo, is first broadcast on CBS: "What a Night for a Knight".
• September 20 – The very last theatrical Warner Bros. cartoon is released: the Merrie Melodies short Injun Trouble.
• September 22 – San Francisco Giant Willie Mays becomes the first player since Babe Ruth to hit 600 career home runs.
• September 22 – September 25 – An Islamic conference in Rabat, Morocco, following the al-Aqsa Mosque fire (August 21), condemns the Israeli claim of ownership of Jerusalem.
• September 23
  • China carries out an underground nuclear bomb test.
  • Butch Cassidy and the Sundance Kid (directed by George Roy Hill and starring Paul Newman and Robert Redford) opens to limited release in the U.S.
• September 24 – The Chicago Eight trial begins in Chicago, Illinois.
• September 25 – The Organisation of the Islamic Conference is founded.
• September 26
  • The Beatles release their Abbey Road album, receiving critical praise and enormous commercial success.
  • The Brady Bunch is broadcast for the first time on ABC.
• September 28 – The Social Democrats and the Free Democrats receive a majority of votes in the German parliamentary elections, and decide to form a common government.

September - 1968

• September 6
  • Swaziland becomes independent.
  • 150 women (members of New York Radical Women) arrive in Atlantic City, New Jersey to protest against the Miss America Pageant, as exploitative of women. Led by activist and author Robin Morgan, it is one of the first large demonstrations of Second Wave Feminism as Women's Liberation begins to gather much media attention.
• September 11
  • The International Association of Classification Societies (IACS) is founded.
  • French General René Cogny and 94 others die in an Air France Caravelle jetliner crash near Nice in the Mediterranean.
• September 13
  • Albania officially retreats from the Warsaw Pact upon the Soviet Union-led Warsaw Pact invasion of Czechoslovakia, having already ceased to participate actively in Pact activity since 1962.
  • US Army Maj. Gen. Keith L. Ware, WWII Medal of Honor recipient, is killed when his helicopter is shot down in Vietnam. He is posthumously awarded the Distinguished Service Cross.
  • Agreement for merger between the General Electric Company and English Electric, the largest industrial merger in the UK up to this date.
• September 14 – Detroit Tiger Denny McLain becomes the first baseball pitcher to win 30 games in a season since 1934. He remains the last to accomplish the feat.
• September 17 – The D'Oliveira affair: The Marylebone Cricket Club tour of South Africa is cancelled when the South Africans refuse to accept the presence of Basil D'Oliveira, a Cape Coloured, in the side.
• September 20 – Hawaii Five-O debuts on CBS, and eventually becomes the longest-running crime show in television history, until Law & Order overtakes it in 2003.
• September 21 – The Soviet's Zond 5 unmanned lunar flyby mission returns to earth, with its first of a kind biological payload intact.
• September 23 – Vietnam War: The Tet Offensive comes to an end in South Vietnam.
• September 24 – 60 Minutes debuts on CBS and is still on the air as of 2016.
• September 27 – Marcelo Caetano becomes prime minister of Portugal.
• September 29 – A referendum in Greece gives more power to the military junta.
• September 30 – At Paine Field, near Everett, Washington in the United States, Boeing officially rolls out its new 747 for the media and the public.

September - 1967

• September 1
  • The Khmer–Chinese Friendship Association is banned in Cambodia.
  • Ilse Koch, known as the "Witch of Buchenwald", commits suicide in the Bavarian prison of Aichach.
• September 3
  • Nguyễn Văn Thiệu is elected President of South Vietnam.
  • At 5:00 a.m. local time, all road traffic in Sweden switches from left-hand traffic pattern to right-hand traffic.
• September 4 – Vietnam War – Operation Swift: The United States Marines launch a search and destroy mission in Quảng Nam and Quảng Tín provinces. The ensuing 4-day battle in Que Son Valley kills 114 Americans and 376 North Vietnamese.
• September 5 – The television series The Prisoner has its world broadcast premiere on the CTV Television Network in Canada.
• September 10 – In a Gibraltar sovereignty referendum, only 44 out of 12,182 voters in the British Crown colony of Gibraltar support union with Spain.
• September 17
  • A riot during a football match in Kayseri, Turkey leaves 44 dead, about 600 injured.
  • Jim Morrison and The Doors defy CBS censors on The Ed Sullivan Show, when Morrison sings the word "higher" from their #1 hit Light My Fire, despite having been asked not to.
• September 18 – Love Is a Many Splendored Thing debuts on U.S. daytime television and is the first soap opera to deal with an interracial relationship. CBS censors find it too controversial and ask for it to be stopped, causing show creator Irna Phillips to quit.
• September 27 – The RMS Queen Mary arrives in Southampton at the end of her last transatlantic crossing.
• September 30 – In the United Kingdom, BBC Radio completely restructures its national programming: the Light Programme is split between new national pop station Radio 1 (modelled on the successful pirate station Radio London) and Radio 2; the cultural Third Programme is rebranded as Radio 3; and the primarily-talk Home Service becomes Radio 4.