Sped Mod 2 By ekortje2 Apr 6, 1917 U.S. entered WWI Mar 19, 1918 Time Zones are established Oct 9, 1919 Black Sox Scandal Jan 10, 1920 League of Nations established Nov 2, 1920 First Radio Broadcast Jul 2, 1921 President Harding declares peace with Germany, Austria, and Hungary Jan 25, 1924 First Winter Olympics Oct 4, 1927 Mount Rushmore is started to be built Jul 17, 1928 Amelia Earhart flies across Atlantic Mar 3, 1931 Star-Spangled Banner becomes National Anthem