January 1 – The Uniform Monday Holiday Act takes effect: Washington's Birthday and several other Federal holidays are always observed on certain Mondays.

January 2 – A ban on radio and television cigarette advertisements goes into effect in the United States.

January 25 – In Los Angeles, Charles Manson and three female "Family" members are found guilty of the 1969 Tate-LaBianca murders.

January 31 – Apollo program: Apollo 14 (carrying astronauts Alan Shepard, Stuart Roosa, and Edgar Mitchell) lifts off on the third successful lunar landing mission.

February 9 – The 6.5–6.7 Mw Sylmar earthquake hits the Greater Los Angeles Area with a maximum Mercalli intensity of XI (Extreme), killing 64 and injuring 2,000.

February 11 – The US, UK, USSR and others sign the Seabed Treaty, outlawing nuclear weapons on the ocean floor.

March 8 – Boxer Joe Frazier defeats Muhammad Ali at Madison Square Garden.

March 29 – U.S. Army Lieutenant William Calley is found guilty of 22 murders in the My Lai massacre and sentenced to life in prison (later pardoned).

April 9 – Charles Manson is sentenced to death; in 1972, the sentence for all California Death Row inmates is commuted to life imprisonment.

April 20 – Swann v. Charlotte-Mecklenburg Board of Education: The Supreme Court of the United States rules unanimously that busing of students may be ordered to achieve racial desegregation.

April 24 – Five hundred thousand people in Washington, DC and 125,000 in San Francisco march in protest against the Vietnam War.

May 3 – A Harris Poll claims that 60% of Americans are against the Vietnam War.

May 30 – Mariner program: Mariner 9 is launched toward Mars.

June 10 – The U.S. ends its trade embargo of China.

June 13 – Vietnam War: The New York Times begins to publish the Pentagon Papers.

June 30 – New York Times Co. v. United States: The U.S. Supreme Court rules that the Pentagon Papers may be published, rejecting government injunctions as unconstitutional prior restraint.

July 3 – Jim Morrison, lead singer and lyricist of The Doors, is found dead in his bathtub in Paris, France.

July 19 – The South Tower of the World Trade Center is topped out at 1,362 feet (415 m), making it the second tallest building in the world.

July 26 – Apollo 15 (carrying astronauts David Scott, Alfred Worden, and James Irwin) is launched.

August 15 – President Richard Nixon announces that the United States will no longer convert dollars to gold at a fixed value, effectively ending the Bretton Woods system.

August 20 – The USS Manatee (AO-58) spills 1,000 US gallons (3,800 L) of fuel oil on President Nixon's Western White House beach in San Clemente, California.

September 8 – In Washington, DC, the John F. Kennedy Center for the Performing Arts is inaugurated, with the opening feature being the premiere of Leonard Bernstein's Mass.

September 9 – September 13 – Attica Prison riots: – A revolt breaks out at the maximum-security prison in Attica, New York. In the end, state police and the United States National Guard storm the facility; 42 are killed, 10 of them hostages.

October 1 – Walt Disney World opens in Orlando, Florida.

October 29 – Vietnam War – Vietnamization: The total number of American troops still in Vietnam drops to a record low of 196,700 (the lowest since January 1966).

November 12 – Vietnam War – Vietnamization: U.S. President Richard M. Nixon sets February 1, 1972, as the deadline for the removal of another 45,000 American troops from Vietnam.

November 13 – Mariner program: Mariner 9 becomes the first spacecraft to enter Mars orbit successfully.

November 15 – Intel releases the world's first commercially available microprocessor.

November 24 – During a severe thunderstorm over Washington, a man calling himself D. B. Cooper parachutes from the Northwest Orient Airlines plane he hijacked, with US$200,000 in ransom money, and is never seen again.

December 18 – The U.S. dollar is devalued for the second time in history.

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• Cold War (1945–1991)

• Space Race (1957–1975)

• Vietnam War, U.S. involvement (1962–1973)

• Détente (c. 1969–1979)

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