Although we own a few resources provided through ProQuest, Drake does not have access to the Proquest Digital Sanborn maps database. 

University of Iowa is supposed to have access to this database.  I would contact the library there concerning any access for non-affiliated persons.

Library of Congress has not digitized any of the Chicago maps:

http://www.loc.gov/rr/geogmap/sanborn/city.php?CITY=Chicago&stateID=15

Please see:

https://www.newberry.org/fire-insurance-maps

for additional resources.

Thank you.