To me, some of the most interesting stuff about railroad history is not about the trains or the railroads themselves, but how they affected the places in which they operated. The oft-cited cliche is that the railroads built this country, and although they certainly had an effect on the movement of people westward, some of the strongest effects can be witnessed around cities. Today’s Harlem, Hudson, and New Haven Lines played an immense part in the growth of New York City’s suburbs, and other railroads played a similar part in other major cities. Trains provided easy access to the city’s...