In 1848, the US obtained California and a few different domains from Mexico through the Settlement of Guadalupe Hidalgo, which closed the Mexican-American Conflict.

This huge land securing included California as well as parts of present-day Nevada, Utah, Arizona, New Mexico, Colorado, and Wyoming. The treaty was crucial to the nation's westward expansion, making it easier for the Gold Rush and increasing the number of people living in these areas. It likewise escalated banters over the expansion of bondage into the recently gained lands, adding to the developing strains that would ultimately prompt the Nationwide conflict, making it a milestone occasion in U.S. history.