California became a state on September 9, 1850, as part of the Compromise of 1850. This agreement aimed to resolve tensions between free and slave states following the Mexican-American War. California's rapid population growth, fueled by the Gold Rush of 1849, made it necessary to establish a formal government and join the Union. As a free state, California's admission helped maintain the balance between free and slave states in the United States. The state's diverse population and economic potential contributed to its significance in American history, shaping its identity and role in the nation.