Chicago Tunnels

http://en.wikipedia.org/wiki/Chicago_Tunnel_Company

http://www.encyclopedia.chicagohistory.org/pages/3720.html,
http://www.encyclopedia.chicagohistory.org/pages/367.html

http://www.michaelearley.info/deeptunnel
http://www.youtube.com/watch?v=Cvl9jIhMk-w,
http://www.flickr.com/photos/michaelinitaly/sets/72157624113008795/

http://web.archive.org/web/20051105090819/http://wgntv.trb.com/wgntv-news-101005tunnel,1,1202440.story

http://en.wikipedia.org/wiki/Thornton_Quarry,
http://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan