The Forty-Niners moved west primarily because of the discovery of gold in California in 1848, which sparked the California Gold Rush. The news of gold spread rapidly, causing a massive wave of migration in 1849 from across the United States and the world. These fortune seekers, known as Forty-Niners, were drawn by the opportunity to find gold, get rich quickly, and pursue new economic opportunities. The rush was fueled by the dream of wealth, as well as other reasons such as the desire for land, starting businesses, and adventure. The migration was part of the larger westward expansion inspired by the idea of "Manifest Destiny," the belief that Americans were destined to expand across the continent. Routes to California included traveling by sea via the Panama shortcut or Cape Horn, and overland by wagon train, each with significant challenges. Though many came for gold, some ended up staying to pursue farming, business, and other livelihoods in the rapidly growing communities of California. San Francisco became the gateway to California during this rush. In summary, the Forty-Niners moved west because of the promise of gold discovered in California, the lure of quick wealth, economic opportunities, adventure, and the broader context of American territorial expansion westward at the time.