The major event that impacted the ecology of the Rocky Mountains in the late 1800s was The Gold Rush.

This period saw a large influx of miners and settlers, leading to significant environmental changes due to mining activities, deforestation, and increased human presence, which affected local ecosystems and wildlife.The arrival of thousands of miners and settlers led to widespread deforestation, mining, and the construction of settlements, which disrupted natural habitats. Mining activities released harmful chemicals into rivers and soils, affecting water quality and plant life. Wildlife faced habitat loss and increased hunting pressure, leading to a decline in certain species. These environmental changes altered the natural landscape and ecosystems of the Rockies, with some effects lasting well into the future. The Gold Rush forever changed the ecological balance of the Rocky Mountain region.