A boomtown is a community that undergoes sudden and rapid population and economic growth, or that is started from scratch. The growth is normally attributed to the nearby discovery of a precious resource such as gold, silver, or oil, although the term can also be applied to communities growing very rapidly for different reasons, such as a proximity to a major metropolitan area, huge construction project, or attractive climate.

The California gold rush (1848–1855) was a gold rush that began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the United States and abroad. The sudden influx of gold into the money supply reinvigorated the American economy; the sudden population increase allowed California to go rapidly to statehood in the Compromise of 1850. The Gold Rush had severe effects on Native Californians and accelerated the Native American population's decline from disease, starvation, and the California genocide.