- Sep 1 Failed assassination attempt on Jordanian king Hussain
- Sep 1 Jose Velasco Ibarra re-elected president of Ecuador
- Sep 2 US Open first Grand Slam tournament tiebreak is used to decide a set at 6-6; first player to reach 5 points with sudden death at 4-4
- Sep 3 After playing a NL record 1,117 consecutive MLB games, Chicago Cubs outfielder Billy Williams asks to sit out
- Sep 3 Bill Halley & Comets reject $30,000 for 15 date tour of Australia
Election of Interest
Sep 4 Marxist Salvador Allende wins a narrow plurality of votes in Chile's presidential election
Salvador Allende
- Sep 4 An Irish Republican Army (IRA) member, Michael Kane (35), is killed in the premature explosion of the bomb he was planting at an electricity transformer in Belfast
- Sep 5 Estimated 15 cm (6") of rainfall, Bug Point, Utah (state record)
- Sep 6 Palestinians seize 3 airliners
- Sep 6 USSR performs nuclear test at Eastern Kazakh/Semipalitinsk USSR
Event of Interest
Sep 7 Jerry Lewis' 5th Muscular Dystrophy telethon
Jerry Lewis
- Sep 7 Popular Front for the Liberation of Palestine hijacks 4 planes and forces them to land at Dawson's Field, Jordan
- Sep 7 White Sox use record 41 players in doubleheader & lose both games
- Sep 7 Donald Boyles sets record for highest parachute jump from a bridge, by leaping off of 1,053' Royal George Bridge in Colorado
- Sep 7 Fighting between Arabic guerillas and government forces in Amman, Jordan.
- Sep 8 Black September hijackings begin, three airliners hijacked and blown up by Popular Front for the Liberation of Palestine
- Sep 9 Bowie Kuhn suspends Denny McLain for carrying a gun
- Sep 9 Feyenoord wins soccer's Club World Cup
- Sep 11 88 of the hostages from the Dawson's Field hijackings are released. The remaining hostages, mostly Jews and Israeli citizens, are held until September 25.
- Sep 11 The Ford Pinto is introduced.
- Sep 12 Soviet unmanned spacecraft Luna 16 launched to the moon
- Sep 12 Phyllis Ann George (Texas), 21, crowned 43rd Miss America 1971
- Sep 12 Supersonic airliner Concorde lands for the 1st time at Heathrow airport
- Sep 12 US LSD professor Timothy Leary escapes from California jail
- Sep 12 Palestinian terrorists blow up three hijacked airliners in Jordan, continuing to hold the passengers hostage in various undisclosed locations in Amman.
Tennis Open
Sep 12 US Open Women's Tennis: Margaret Court of Australia successfully defends title; beats Rosemary Casals 6-2, 2-6, 6-1
Rosemary Casals
- Sep 13 1st NYC Marathon won by Gary Muhrcke in 2:31:38
- Sep 13 IBM announces System 370 computer
- Sep 13 Palestine guerillas conquer Irbid Jordania
- Sep 13 US Open Men's Tennis: Ken Rosewall wins 2nd US title; beats fellow Australian Tony Roche 2-6, 6-4, 7-6, 6-3
- Sep 14 Economic Council for Northern Ireland holds its first meeting
Event of Interest
Sep 15 Decca awards Bing Crosby a 2nd platinum disc for selling 300 million
Bing Crosby
- Sep 15 PLO leader Arafat threatens to make a cemetery of Jordan
- Sep 15 Rotterdam dock strikes end
- Sep 15 Officers of the Royal Ulster Constabulary (RUC) in Northern Ireland vote narrowly in favour of remaining unarmed
- Sep 16 King Hussein of Jordan forms military government
- Sep 17 Jordan launches offensive against guerrilla army
- Sep 17 WSWP TV channel 9 in Grandview, WV (PBS) begins broadcasting
Event of Interest
Sep 19 "The Mary Tyler Moore" show premieres on CBS
Mary Tyler Moore
Event of Interest
Sep 20 Jim Morrison found guilty of "open profanity and indecent exposure" after allegedly exposing himself at a concert in Miami in 1969
Jim Morrison
- Sep 20 Soviet spcecraft Luna 16 lands on Moon's Mare Fecunditatis, drills core sample
- Sep 21 "Monday Night Football" premieres on ABC - Browns 31, Jets 21
- Sep 21 KAPP TV channel 35 in Yakima, WA (ABC) begins broadcasting
- Sep 21 Soviet space probe Luna 16 leaves the Moon
- Sep 21 Oakland A's Vida Blue no-hits Minnesota Twins, 6-0
- Sep 21 New York Times starts first modern op-ed page
Event of Interest
Sep 22 US President Richard Nixon requests 1,000 new FBI agents for college campuses
Richard Nixon
Album Release
Sep 25 Ringo Starr releases his album "Beaucoups of Blues"
Ringo Starr
- Sep 26 The Laguna Fire starts in San Diego County, California, burning 175,425 acres (710 km²).
- Sep 26 A groups of Protestant youths attack the Catholic Unity Flats as rioting continues in the Protestant Shankill Road area
- Sep 27 Ken Boswell sets 2nd baseman record of 85 games without an error
- Sep 28 "Words & Music" debuts on NBC-TV
Event of Interest
Sep 28 Anwar Sadat replaces Gamal Abdel Nasser as acting Egyptian President
Anwar Sadat