1930-1939 By ToriRogers Jun 17, 1930 Herbert Hover signs the Smoot bill Mar 12, 1931 Mahatma Gandhi and his followers begin a 200 mile march to the salt beds of Jalalpur. Apr 25, 1931 The United States embarks on an ambitious programme of Public Works to regenerate the economy including the building of the Boulder Dam ( Hoover Dam ) Feb 25, 1939 all of europe enter the war