January 5 - The first woman governor in the U.S. is Nellie Taylor Ross of Wyoming.
February 25 - Glacier Bay National Monument is established in Alaska.
March 31 - Mt. Rushmore National Memorial is authorized by Congress with sculptor Gutzon Borgium to carve Presidents George Washington, Abraham Lincoln, Thomas Jefferson and Theodore Roosevelt.
April 29 - Dr. Florence Sabin is the first woman elected to the U.S. National Academy of Science.
May 5 - John T. Scopes, a teacher in Dayton, Tennessee, is arrested for teaching Darwin's theory of evolution.
September 13 - Xavier University in New Orleans, Louisiana is the first U.S. university for African Americans.
November 9 - The discovery of cosmic rays is announced in Madison, Wisconsin.