In the glaciated regions of the Rocky Mountains, essentially from the Yellowstone area in northwestern Wyoming, United States, to Yukon, Canada, gravel-bed rivers are disproportionately important to regional biodiversity and to landscape-scale ecological integrity. Research conducted in this mountain region, across a wide variety of fields in ecology and diverse taxa, has highlighted the importance of these gravel-bed rivers to an unexpectedly high proportion of the region’s aquatic, avian, and terrestrial species. Although gravel-bed river floodplains play a disproportionately important role in sustaining native plant and animal biodiversity, they have also been disproportionately affected by human infrastructure and activities.