On January 24, 1848, James W. Marshall noticed some flakes of gold in the American River while building a sawmill. That discovery started what became known as the California Gold Rush, the frenzied migrations of thousands to California to strike it rich. At that time, California was still technically part of Mexico. Only a week later, The United States purchased land that later became California and other southwestern states for only $15 million. If Mexico had only knwn.
The Gold Rush caused an increase in California's population from 2,700 to 200,000 in two years. Few people actually became wealthy from panning gold but revenue increased enough to help expand the American West.
One person who did become wealthy was Levi Strauss, an immigrant from Bavaria who was a traveling merchant specializing in trousers made from sailcloth held together with copper rivets. These, of course, were the precursors of modern jeans.