Peering out from their open cockpits, early airmail pilots sought visual references on the ground to help guide their way. Rivers and particularly railroads were helpful guidance tools. When all else might fail, a pilot who could find the right railroad to follow could fly directly to his destination. Maps were another important tool. Before maps were created specifically for aviators, pilots used ordinary maps to help find their way over new territory.
Map reading was not a prerequisite for employment as an airmail pilot, because there were no flight maps. Instead there were flight directions compiled by other pilots and station managers. They read something like this: "From the end of the runway follow the main road keeping to the left of the small lake and pass straight over the big tree at the end. Then head for the water tower in the distance." On a foggy morning that water tower might as well have been on Mars.