Let's give credit to the father of Orienteer Kansas - George McCleary. It was his idea of white contours making use of only two colors and using the white background as a third color, taught in his cartographic design classes It was a step up from many of the local black & white maps that were simply inked with coarse Zipatone screens. The use of finer screens and halftones just brought up the standards. Two colors just brought it a little closer to the full color stuff. Then everyone just decided to not mess around anymore and produce the color maps at IOF standards. We were then inspired by Eric Weyman and Pat Dunlavey's first Silvermine map - that was in the late 70s.