January 11 – Super Bowl IV: The Kansas City Chiefs beat the favored Minnesota Vikings 23–7.

February 18 – A jury finds the Chicago Seven defendants not guilty of conspiring to incite a riot, in charges stemming from the violence at the 1968 Democratic National Convention.

March 6 – A bomb constructed by members of the Weathermen and meant to be planted at a military dance in New Jersey explodes, killing 3 members of the organization.

March 21 – The first Earth Day proclamation is issued by San Francisco Mayor Joseph Alioto.

April 1 – President Richard Nixon signs the Public Health Cigarette Smoking Act into law, banning cigarette television advertisements in the United States, starting on January 1, 1971.

April 10 – Paul McCartney announces that The Beatles are breaking up.

April 22 – The first Earth Day is celebrated in the U.S.

April 29 – The U.S. invades Cambodia to hunt out the Viet Cong; widespread, large antiwar protests occur in the U.S.

May 1 – President Richard Nixon orders U.S. forces to cross into neutral Cambodia, threatening to widen the Vietnam War, sparking nationwide riots and leading to the Kent State Shootings.

May 4 – Kent State shootings: Four students at Kent State University in Ohio are killed and 9 May 8 May 8 – Hard Hat riot: Unionized construction workers attack about 1,000 students and others protesting the Kent State shootings near the intersection of Wall Street and Broad Street and at New York City Hall.

June 11 – The United States gets its first female generals: Anna Mae Hays and Elizabeth P. Hoisington

June 22 – U.S. President Richard Nixon signs a measure lowering the voting age to 18. (Voting Rights Act Amendments of 1970)

June 24 – The United States Senate repeals the Gulf of Tonkin Resolution.

June 28 – U.S. ground troops withdraw from Cambodia.

July 4 – American Top 40, a nationally syndicated radio program featuring a countdown of the top 40 hits of the past week according to the Billboard Hot 100, premieres. Hosted by Casey Kasem, the show is a major success.

August 26 – The Women's Strike For Equality takes place down Fifth Avenue in New York City.

September 5 – Vietnam War – Operation Jefferson Glenn: The United States 101st Airborne Division and the South Vietnamese 1st Infantry Division initiate a new operation in Thua Thien Province (the operation ends in October 1971).

September 7 – An anti-war rally is held at Valley Forge, Pennsylvania, attended by John Kerry, Jane Fonda and Donald Sutherland.

September 9 – Elvis Presley begins his first concert tour since 1958 in Phoenix, Arizona at the Veterans Memorial Coliseum.

September 13 – The first New York City Marathon begins.

September 18 – Jimi Hendrix dies of alcohol-related complications.

September 29 – The U.S. Congress gives President Richard Nixon authority to sell arms to Israel.

October 4 - National Educational Television ends operations, being succeeded by PBS September 23.

October 4 - In Los Angeles, Rock and blues singer Janis Joplin dies in her hotel room, from an overdose of heroin.

October 8 – Vietnam War: In Paris, a Communist delegation rejects U.S. President Richard Nixon's October 7 peace proposal as "a maneuver to deceive world opinion."

October 12 – Vietnam War: U.S. President Richard Nixon announces that the United States will withdraw 40,000 more troops before Christmas.

November – The 1969–1970 recession ends.

November 3 – Democrats sweep the U.S. Congressional midterm elections; Ronald Reagan is reelected governor of California; Jimmy Carter is elected governor of Georgia.

November 4 – Vietnam War – Vietnamization: The United States turns control of the air base in the Mekong Delta to South Vietnam.

November 5 – Vietnam War: The United States Military Assistance Command in Vietnam reports the lowest weekly American soldier death toll in 5 years (24 soldiers die that week, which is the fifth consecutive week the death toll is below 50; 431 are reported wounded that week, however).

November 17 – Vietnam War: Lieutenant William Calley goes on trial for the My Lai massacre.

November 18 – U.S. President Richard Nixon asks the U.S. Congress for US$155 million in supplemental aid for the Cambodian government (US$85 million is for military assistance to prevent the overthrow of the government of Premier Lon Nol by the Khmer Rouge and North Vietnam).

December 2 – The United States Environmental Protection Agency begins operations.

December 23 – The North Tower of the World Trade Center is topped out at 1,368 feet (417 m), making it the tallest building in the world.

December 29 – U.S. President Richard Nixon signs into law the Occupational Safety and Health Act.

 

Ongoing

• Cold War (1945–1991)

• Space Race (1957–1975)

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

• Détente (c. 1969–1979)

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