Why our Grand Canyon mileage is in tenths of a mile

You may have noticed that our Grand Canyon guidebook is measured in tenths of a mile, and not our standard hundredths like our other rivers. We collected our data using phones and our GPS units, which allowed us to be more exact than what we’ve published, however, there are two important reasons for not having this precision.

Photo by Skip Volpert of Idaho River Journeys

1) We wanted our data to align with the NPS and other guidebooks

When we originally published our data by the hundredths of a mile, we found that there were discrepancies between what we recorded and the published material by the National Park Service. These differences are expected and are due to different GPS pin locations. Additionally, when we tested our data with friends, they all used different guidebooks, and these discrepancies were distracting. By providing less precise data, they aligned better, and the distraction disappeared. The differences also implied that one of the sources was wrong (our data verse theirs) which is not true due to the reasons listed above of different pin placements.

2) Precision is less necessary in the Grand Canyon

Rapids and camps are quite obvious in the Grand Canyon, and more importantly, points of interest don’t tend to stack up on one another. If camps were like the Rogue River, where in a quarter-mile you may have seven distinct camps, then mileage done in hundredths of a mile would be required. On the Grand Canyon though, this is not the case, so points of interest don’t have to be assigned to the foot.

It’s only going to improve over time

When we started this mapping project we dove into it with the mindset that this is forever a work in progress. We never publish a guidebook and consider it done. We are constantly making adjustments, re-writing content, and re-evaluating our data. With that principle in mind, we will one day be able to publish our data to the exact distance, but for now, this solution works out fine.