Creation of the Matthes-Evans United States Geological Survey topographic map of the Grand Canyon was a herculean effort. It was the most impressive mapping activity to ever take place at the Grand Canyon, considering the surveying tools that were available at the time. Field work on the Matthes-Evans map began in 1902, but publication of the map did not occur until 1927. This was a 25 year effort, facing extremely challenging field conditions. This presentation will describe the surveying methods and tools used, and the field work required to prepare the Matthes-Evans Map. Extremely challenging terrain and climate made field work quite difficult. Matthes and others produced firsthand accounts that provide a historical record of the mapmaking effort and some of the trials and tribulations encountered by the surveyors. These sources, plus the author’s onsite visits to triangulation stations and benchmarks provide the basis for the story of the map’s creation.