On Monday, I finally made it to the headwaters of the Colorado River. Amy and I hiked 16 miles round trip to follow the river through Rocky Mountain National Park to its source on the Continental Divide. For the geography, hydrology, and water-policy nerds among us, it’s a really interesting place. Pointing to a single starting point for a river as enormous as this one is a dubious idea, but we agreed that this is about as precise as one can get.