TTH Timeline Assignment #3 By Theo Hallie 1921 Warren Harding Becomes President 1923 Calvin Coolidge Becomes President 1926 Liquid Rocket Fuel Invented 1929 Herbert Hoover Becomes President 1931 Star Spangled Banner Adopted as National Anthem 1933 Franklin D. Roosevelt Becomes President 1937 Modern Day Digital Computer Invented 1938 First Minimum Wage is Passed at $0.25/hr 1939 World War II Begins