In 1995, the permitted ski areas were manuscripted on overlays to 1:24,000 scale quads. The base layers to which the data layer is geo-referenced are formatted 1:24,000 scale, 7.5 minute orthophoto quadrangles from 1989 high altitude photography (1:40,000 scale). Permit area maps were used to obtain boundary locations. Those maps ranged in scale from 4 inches per mile to 1 inch per mile. Map features that were referenced in the map manuscripting on the quad overlays included ridges, section lines, and State Highway 2 (for the Steven's Pass Ski Area).
The polygons were manuscripted on film overlays on the orthophoto base layer. In addition, one of three quad positive base layers were used, depending on what was available and most recent. The quad base layers, listed in increasing age, include: Primary Base Series layers (the contour layer and the base layer), the USGS Provisional Edition quad map, or the Transportation System Update Layer.