This section of the Timeline of United States history concerns events from 1900 to 1929.
1900 - U.S. population exceeds 75 million
1900 - U.S. helps put down Boxer Rebellion
1900 - 1900 Galveston hurricane
1901 - William McKinley assassinated
1901 - Theodore Roosevelt becomes President
1901 - U.S. Steel founded by John Pierpont Morgan
1901 - Hay–Pauncefote Treaty
1902 - Drago Doctrine
1902 - First Rose Bowl game played
1902 - Newlands Reclamation Act
1903 - Great Train Robbery movie opens
1903 - Harley-Davidson Motor Company created
1903 - Ford Motor Company formed
1903 - First World Series
1903 - Elkins Act
1903 - Big Stick Diplomacy
1903 - Hay–Bunau-Varilla Treaty
1903 - Hay–Herrán Treaty
1903 - Department of Commerce and Labor created
1903 - The Wright brothers make their first powered flight in the Wright Flyer
1904 - Roosevelt Corollary to Monroe Doctrine
1904 - Panama Canal Zone acquired
1904 - Worlds Fair St. Louis
1905 - Niagara Falls conference
1905 - Industrial Workers of the World
1906 - Susan B. Anthony dies
1906 - Algeciras Conference
1906 - Pure Food and Drug Act and Meat Inspection Act
1906 - Hepburn Act
1906 - Theodore Roosevelt negotiates Treaty of Portsmouth, receives Nobel Peace Prize
1906 - San Francisco earthquake
1907 - Oklahoma becomes a state
1907 - Gentlemen's Agreement
1907 - Coal mine explodes in Monongah, West Virginia, killing at least 361. Worst industrial accident in American history.
1908 - Ford Model T appears on market
1908 - Root–Takahira Agreement
1908 - Federal Bureau of Investigation established
1908 - Aldrich–Vreeland Act
1909 - The U.S. penny is changed to the Abraham Lincoln design
1909 - William Howard Taft becomes President
1909 - Robert Peary claims to have reached the North Pole
1909 - NAACP founded by W. E. B. Du Bois
1909 - Payne–Aldrich Tariff Act
1909 - Taft implements Dollar Diplomacy
1909 - Pinchot–Ballinger controversy
1910 - Mann–Elkins Act
1910 - Mann Act
1911 - Supreme Court breaks up Standard Oil
1911 - Triangle Shirtwaist fire
1911 - First ever Indianapolis 500 is staged; Ray Harroun is the first winner
1912 - RMS Titanic sinks
1912 - New Mexico and Arizona become states
1912 - Girl Scouts of the USA was started by Juliette Gordon Low
1912 - Theodore Roosevelt shot, but not killed, while campaigning for the Bull Moose Party
1913 - Woodrow Wilson becomes President
1913 - 16th Amendment, establishing an income tax
1913 - End of the Philippine–American War
1913 - The Armory Show opens in New York City introducing Modern art both American and European to the American public.
1913 - 17th Amendment, establishing direct election of U.S. Senators.
1913 - Underwood Tariff
1913 - Henry Ford develops the modern assembly line
1914 - Mother's Day established as a national holiday
1914 - Federal Trade Commission created
1914 - Clayton Antitrust Act
1914 - ABC Powers
1915 - The Birth of a Nation opens
1915 - RMS Lusitania sunk
1916 - U.S. acquires Virgin Islands
1916 - Jeannette Rankin first woman elected to U.S. congress
1916 - Louis Brandeis appointed to Supreme Court
1916 - Adamson Railway Labor Act
1916 - Federal Farm Loan Act
1916 - Jone Act
1917 - Zimmermann Telegram
1917 - U.S. enters World War I
1917 - Espionage and Sedition Acts
1917 - Lansing–Ishii Agreement
1917 - NHL
1917 - U.S. Virgin Islands purchased from Denmark
1917-1920 - First Red Scare, marked by a widespread fear of Bolshevism and anarchism
1918 - President Wilson's Fourteen Points, which assures citizens that the Great War was being fought for a moral cause and for postwar peace in Europe
1918 - Treaty of Versailles ends World War I
1919 - Theodore Roosevelt dies
1919 - United States Senate rejects Treaty of Versailles and League of Nations
1919 - 18th Amendment, establishing Prohibition
1919 - Black Sox Scandal during that year's World Series, wherein the fallout lasts for decades
1920 - 19th Amendment, granting women the right to vote
1920 - Sacco and Vanzetti arrested
1920 - First radio broadcasts in Pittsburgh and Detroit
1920 - Volstead Act
1920 - Esch–Cummins Act
1920 - NFL
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
1929 - The Great Depression Starts
1932 - Elizabeth Taylor was born
Timeline of United States history (1900–29) Wikipedia (Text) CC BY-SA