A major earthquake—later estimated to be between 7.7 and 7.9 on the Richter scale—struck San Francisco at 5:12 a.m. The devastation grew as broken gas lines caused widespread fires and much of the city was destroyed. As many as 3,000 people were killed, and more than half of the survivors found themselves homeless.
The Eighteenth Amendment to the Constitution forbidding the manufacture, sale, transportation, import, and export of “intoxicating liquors” was ratified, instituting Prohibition nationwide. The amendment was repealed by the Twenty-first Amendment in 1933.
American forces took part in the forty-seven-day Meuse-Argonne offensive. The Allies advanced through the Argonne Forest and pushed the German line back until, cornered and with no hope for success, the Germans agreed to cease fire and an armistice on November 11.
Wilson released a decoded telegram from German foreign minister Arthur Zimmermann to Mexico. Zimmermann proposed that, if the US entered the war, Mexico go to war with the US as a German ally. Zimmermann promised that if Mexico allied with Germany, Germany would provide “financial support and an understanding on our part that Mexico is to reconquer lost territory in Texas, New Mexico, and Arizona.”