The Sanborn Insurance Maps appear to be good tools for those researching rail roads from the 1890s and 1900s. The Library of Congress has done a good job of putting some of them on its website. So far the Jersey section covers some important rail road towns including Bound Brook, Heightstown, Lambertville, Boonton, Newark, etc. Link to maps below...
https://www.loc.gov/collections/sanborn ... =1&st=list" onclick="window.open(this.href);return false;
https://www.loc.gov/collections/sanborn ... =1&st=list" onclick="window.open(this.href);return false;