I’m reading Iron Empires now. It’s about the financial side of railroading in the 19th century, which is the part I find most interesting when it comes to 18xx. It’s very easy to understand why Erie is usually a bad company in 18xx when reading it (it was famous for being looted several times). https://www.amazon.com/Iron-Empires-Robber-Railroads-America-ebook/dp/B07T1FT3D6/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1619386390&sr=1-2