Chicago Rapid Transit Company

https://en.wikipedia.org/wiki/Chicago_Rapid_Transit_Company ,

https://upload.wikimedia.org/wikipedia/commons/5/5e/Chicago_Elevated_Map_1913.jpg ,

https://en.wikipedia.org/wiki/Chicago_%22L%22_rolling_stock#3200-series ,

https://en.wikipedia.org/wiki/Chicago_%22L%22_rolling_stock#/media/File:CTA_train_NE_corner.jpg ,

https://en.wikipedia.org/wiki/7000-series_(CTA)