The "Gold Rush Era" refers to a period in the mid-19th century when large numbers of people flocked to areas where gold was discovered, particularly in the United States. The most famous event was the California Gold Rush of 1849, which began when gold was found at Sutter's Mill. This discovery led to a massive influx of prospectors, known as "forty-niners," seeking fortune and opportunity. The Gold Rush significantly impacted the economy and population of the regions involved. Towns sprang up rapidly, and many became boomtowns, while others faded away once the gold was depleted. The era also contributed to the westward expansion and development of infrastructure, including railroads and telegraph lines, shaping the future of the American West.