California and other land was opened up for Americans after the end of the Mexican War. this happened shortly after John William Marshal found the gold flakes, so it was perfect timing; the California colony was just there for the U.S. to claim it as its own. As people headed to California, gold fever affected the progress of world known industries. Many people could not resist the chance of an easy fortune, and left their families, friends, and pretty much everything that was familiar to them to be part of the gold rush. The population of California skyrocketed to previously unknown amounts, and was increasing every day. This resulted in the question of allowing California into the US as a new state. This opened the debate as to if a new state should be allowed to be a free state or a slave state and who should make that determination. With that debate, the Civil War had sparked. The Gold Rush also made California irresistable to the U.S. government because of all of the wealth it was bringing, so after a lot more debate, California became the 31st state in 1850.