1900
- An epidemic of bubonic plague centered on San Francisco's Chinatown begins, the first plague epidemic in the continental United States (reviled investigator Joseph J. Kinyoun pictured)
- The California Automobile Company is founded in San Francisco
- The Sempervirens Club is founded with the goal of preserving old growth coast redwood forest in the Santa Cruz Mountains
- The World's Drinks And How To Mix Them, by William "Cocktail" Boothby, is published by the Palace Hotel, San Francisco