They may be old, but they can contain a wealth of information - or, in this case, confirmation. I had posted before that my HO scale rendition of Union Pacific's Burlington Sub - the erstwhile Chicago and North Western Railway's primary freight entrance to the Beer City - was based upon an alternate history. Well, thanks to the efforts of a fellow aficionado Nick Trimberger one can see the old (proposed) routing of the Fox River Valley RR north-northwest from Turner Junction - now West Chicago, IL - through Crystal Lake and Richmond, IL into Burlington, WI and ultimately Milwaukee. Nick found these gems in the National Archives, and has shared them - along with many other "paper" railroads on his fine blog.
Eureka! (and many thanks, Nick)