The significant historical event that took place in the Rockies during the 1800s is the Gold Rush.

The Gold Rush in the Rocky Mountains, particularly after the discovery of gold in Colorado in 1858, was a transformative event that attracted thousands of prospectors and settlers to the region. This influx led to the rapid development of mining towns, such as Denver and Boulder, which sprang up to support the growing population of fortune seekers. The Gold Rush spurred economic growth, infrastructure development, and the expansion of railroads, facilitating further exploration of the West. However, this boom also had profound impacts on Native American communities, as mining activities and increased settlement disrupted their traditional lands and lifestyles.