A METHOD FOR ASSESSING THE PLANIMETRIC ACCURACY OF HISTORICAL MAPS - THE CASE OF THE COLORADO-GREEN RIVER SYSTEM

The position of linear elements on historical maps can be digitized an d numerically compared with similar features on modem maps. This allow s for the evaluation of amounts and rates of improvement in cartograph ic accuracy and of die primary sources used for the generation of subs equent maps. A case study of the Colorado-Green River system illustrat es the method and documents die pace of improvement in the cartographi c depiction of the river system as a function primarily of the histori cal pressures of westward expansion.