The Ma & Pa ran between Baltimore, MD and York, PA for 77 miles with something like 110 bridges and approximately 2 miles of straight track. Ran steam until the 1950's. Roundhouse and freight station in Baltimore still stand as well as a number of depots. Awesome little railroad with a long history. Beautiful scenery as most of the line was in the countryside. This RR was where the term "milk run" originated.
This book is still available in paperback. Amazon has it for $24.39 on Prime.