In 1848, the gold discovered in Coloma first brought thousands of miners from Sonora in northern Mexico on the way to the goldfields. So many of them settled in the area north of the Plaza that it came to be known as Sonoratown. The U.S. army swarmed in.

In 1848, California’s new military governor Bennett C. Riley ruled that land could not be sold that was not on a city map.

In 1849, Lieutenant Edward Ord surveyed Los Angeles to confirm and extend the streets of the city. His survey put the city into the real-estate business, creating its first real-estate boom and filling its treasury.

On April 4, 1850, Los Angeles was incorporated as a U.S. city. Five months later, California was admitted into the Union.