* 1920 - 19th Amendment, granting women the right to vote
* 1920 - Sacco and Vanzetti arrested
* 1920 - First radio broadcasts in Pittsburgh, Pennsylvania and Detroit, Michigan
* 1920 - Volstead Act
* 1920 - Esch-Cummins Act
* 1921 - Warren G. Harding becomes President
* 1921 - Washington Disarmament Conference of 1921
* 1921 - Emergency Quota Act
* 1922 - Fordney-McCumber tariff
* 1923 - President Warren G. Harding dies; Calvin Coolidge succeeds him
* 1923 - Teapot Dome Scandal
* 1924 - Immigration Act Basic Law
* 1924 - J. Edgar Hoover is appointed director of the Bureau of Investigation — predecessor to the FBI.
* 1925 - Scopes trial, whose outcome found that the teaching of evolution in the classroom "does not violate church and state or state religion laws but instead, merely prohibits the teaching of evolution on the grounds of intellectual disagreement"
* 1925 - Nellie Tayloe Ross elected governor of Wyoming
* 1925 - WSM broadcasts the Grand Ole Opry for the first time.
* 1926 - NBC founded as the U.S.'s first major broadcast network
* 1927 - Sacco and Vanzetti executed, seven years after they were convicted of murdering two men during an armed robbery in Massachusetts
* 1927 - Charles Lindbergh makes first trans-Atlantic flight
* 1927 - The Jazz Singer, the first "talkie" (motion picture with sound) is released
* 1927 - U.S. citizenship granted to inhabitants of U.S. Virgin Islands
* 1927 - Columbia Broadcasting System (later called CBS) becomes second national radio network in the U.S.
* 1928 - Disney's Steamboat Willie opens, the first animated picture to feature Mickey Mouse
* 1928 - Kellogg-Briand Pact
* 1928 - Amelia Earhart becomes the first woman to fly solo across the Atlantic Ocean.
* 1929 - Herbert Hoover becomes President
* 1929 - St. Valentine's Day massacre
* 1929 - Immigration Act
* 1929 - The Dow Jones Industrial Average plummets a record 68 points over a two-day period, setting off the Wall Street Crash of 1929 and triggering the Great Depression
* 1929 - The Museum of Modern Art opens to the public in New York City
* 1929 - American Samoa officially becomes a U.S. territory