Over wide areas of the earth the railroad has been a decisive instrument in the creation of many of the most important patterns of human geography. Railroads are clearly phenomena of prime geographical interest, yet if it is true that "each means of transport has its own technological characteristics and its spatial layout, or network," it is equally true that their understanding of the inherent geographical implications of these characteristics and networks is far from satisfactory. The following paper attempts to add a further dimension to this common quest by focusing upon the comparative genetic character of two railroad networks.