Like his three previous books in this series, this fourth and final volume is a monumental atlas. It covers the Catskills region from the Hudson Valley to the West Branch Delaware River Valley. Included are the Ulster & Delaware; the Delaware & Northern; the New York, Ontario & Western’s Delhi Branch; and the Catskill Mountain Railroad with its connecting narrow-gauged lines in Greene County. A series of short lines that served individual industries and construction sites are also described along with a few railroads that were partially built but never completed. Included are brief chronologies of the two recent tourist lines: the (second) Catskill Mountain Railroad and the Delaware & Ulster Rail Ride. A catalog of 379 railroad-related industries and facilities is included, and each rail line is illustrated in detail on 191 maps.