Leslie Irvin of the United States makes the first successful voluntary free-fall parachute jump using a new kind of self-contained parachute.

The steel strike of 1919, led by the Amalgamated Association of Iron and Steel Workers, begins in Pennsylvania before spreading across the United States.

The National Football League, (NFL), is founded in the United States.

The National Football League is organized in Canton, Ohio, United States.

In the United States, KDKA of Pittsburgh, Pennsylvania starts broadcasting as the first commercial radio station. The first broadcast is the result of the U.S. presidential election, 1920.

Tulsa Race Riot: A civil unrest in Tulsa, Oklahoma, United States, the official death toll is 39, but recent investigations suggest the actual toll may be much higher.

The Washington Naval Treaty is signed in Washington, D.C., limiting the naval armaments of United States, Britain, Japan, France, and Italy.

In Washington D. C., Charles Evans Hughes signs the Hughes-Peynado agreement, that ends the occupation of Dominican Republic by the United States.

Capital punishment: The first state execution in the United States by gas chamber takes place in Nevada.

American occupying forces leave the Dominican Republic.

Nellie Tayloe Ross of Wyoming is elected the first female governor in the United States.

The American astronomer Edwin Hubble announces the discovery of galaxies outside the Milky Way.

Nellie Tayloe Ross of Wyoming becomes the first female governor in the United States.

The U.S. Zeppelin USS Shenandoah crashes, killing 14.

The Okeechobee Hurricane strikes southeastern Florida, killing upwards of 2,500 people. It is the third deadliest natural disaster in United States history, behind the Galveston Hurricane of 1900 and the 1906 San Francisco earthquake.

The Republic of China is recognised by the United States.

The airship, the Graf Zeppelin completes its first trans-Atlantic flight, landing at Lakehurst, New Jersey, United States.

The United Kingdom, Japan and the United States sign the London Naval Treaty regulating submarine warfare and limiting shipbuilding.

W1XAV in Boston, Massachusetts broadcasts video from the CBS radio orchestra program, ''The Fox Trappers''. The broadcast also includes the first television commercial in the United States, an advertisement for I.J. Fox Furriers, who sponsored the radio show.

The United States officially adopts ''The Star-Spangled Banner'' as its national anthem.

''TIME'' magazine features eccentric American politician William "Alfalfa" Murray on its cover after Murray stated his intention to run for President of the United States.

Amelia Earhart becomes the first woman to fly across the United States non-stop (from Los Angeles to Newark, New Jersey).

Minnie D. Craig becomes the first female elected as Speaker of the North Dakota House of Representatives, the first female to hold a Speaker position anywhere in the United States.

United States recognizes Soviet Union.

Alcatraz Island becomes a United States federal prison.

Oskaloosa, Iowa, becomes the first municipality in the United States to fingerprint all of its citizens.

"Black Sunday Storm", the worst dust storm of the U.S. Dust Bowl.

Dr. Robert Smith takes his last drink, and Alcoholics Anonymous is founded in Akron, Ohio, United States, by him and Bill Wilson.

The National Labor Relations Act, which governs labor relations in the United States, is signed into law by President Franklin D. Roosevelt.

United States Social Security Act passes, creating a government pension system for the retired.

Wallace H. Carothers receives a United States patent for nylon.

Pennsylvania becomes the first (and only) state of the United States to celebrate Flag Day officially as a state holiday.

Theodore Cole and Ralph Roe attempt to escape from the American federal prison on Alcatraz Island in San Francisco Bay; neither is ever seen again.

The Civil Aeronautics Act is signed into law, forming the Civil Aeronautics Authority in the United States.

The Thousand Islands Bridge, connecting New York State, United States with Ontario, Canada over the St. Lawrence River, is dedicated by U.S. President Franklin D. Roosevelt.

Orson Welles broadcasts his radio play of H. G. Wells's ''The War of the Worlds'', causing anxiety in some of the audience in the United States.

Booker T. Washington becomes the first African American to be depicted on a United States postage stamp.

The United States' Under Secretary of State Sumner Welles issues a declaration on the U.S. non-recognition policy of the Soviet annexation and incorporation of three Baltic States: Estonia, Latvia and Lithuania.

World War II: the McCollum memo proposes bringing the United States into the war in Europe by provoking the Japanese to attack the United States.

The United Service Organization (USO) is created to entertain American troops.