1848

Treaty of Guadalupe Hidalgo

Ad for sea transport to the Gold Rush

 • James W. Marshall finds several flakes of gold at a lumber mill he owned in partnership John Sutter, at the bank of the South Fork of the American River, news of which quickly travels around the world (advertisement for transportation to the Gold Rush pictured, right)
 • The California Star and the Californian both cease publication in San Francisco due to losing all their staff to the California Gold Rush
 • The Treaty of Guadalupe Hidalgo (pictured, left) ends the Mexican–American War, and cedes the territory of California (including the San Francisco Bay Area) to the United States from Mexico
 • San Francisco's population is 1,000