These maps are indeed a great source of information on railroading history. They let you see where the rails went and in what time period. They also show major rail customers served by the various lines. The local public library has the Sanborn maps for the Toledo,OH area on line and viewable for free by any library card holder. In addition, you can print and save map pages on your own computer. The viewing software at the library allows you to size the pages so you can see all of the details of the original maps. By saving the largest size, you end up with a .jpg file of 2.5 Mb to 5.5 Mb for each page. The Toledo maps span a period of 1888 to 1950 and later. The maps are a wonderful starting point for modeling a line or area. For example, I am researching the Toledo, St. Louis & Western ( The Cloverleaf Road) in the period just after being taken over by the Nickel Plate Road. 99% of the trackage is gone now, but the maps show it all.