What major event in 1849 encouraged westward expansion?

The California Gold Rush of 1849 is the correct answer because it was a significant catalyst for westward expansion in the United States. When gold was discovered at Sutter's Mill in California, it triggered a massive influx of people seeking fortune and opportunity. This rush led to the migration of hundreds of thousands of individuals, known as "Forty-Niners," to California, transforming the region and solidifying its importance in American history.

The Gold Rush not only spurred the movement of individuals and families but also encouraged the establishment of infrastructure, such as roads, railroads, and towns, as well as the expansion of mining and agriculture. The search for gold highlighted the possibilities of the American West and contributed to the broader idea of Manifest Destiny, the belief that Americans were destined to expand across the continent.

While the Homestead Act provided incentives for settlement, it was introduced later in 1862. The establishment of the Pony Express was significant for communication but did not directly encourage settlement like the Gold Rush did. The opening of the Oregon Trail facilitated earlier migrations, but the Gold Rush represented a defining moment in prompting mass movement towards the West. Thus, the California Gold Rush stands out as the key event driving westward expansion in 1849.