The first overland mail for California leaves St. Louis for San Francisco
Regular overland mail service began from the east coast to California when the first letters and packages departed St. Louis, Missouri. Twenty-four days later, on October 16, the mail arrived in San Francisco, cutting substantially the time the previous sea route had taken for delivery. (By John Osborne)
Source Citation
The American Almanac and Repository of Useful Knowledge for the Year 1860 (Boston: Crosby, Nichols, and Company, 1859), 384.