This was a map of Chicago transit lines when the CRT monopolized the train tracks. From http://forgottenchicago.com/features/remnants-of-the-l/
This is what it says above"
TRANSFERS
Transfers are permitted between Chicago Rapid Transit Company subway and elevated trains and streetcars and buses operated by the Chicago service lines, or between subways and elevated trains and buses of the Chicago motor coach company. Transfers are valid at elevated or subway transfer stations where lines of the Chicago Rapid Company cross, intersect, connect with, converge with or diverge from such street car or motor coach lines. Subway, Elevated, street car and motor coach routes are shown in detail on this map. Transfers are issued ON REQUEST AND AT THE TIME FARE IS PAID by all Subway and Elevated ticket agents on the Rapid Transit System south of Howard Street and next of Desplaines Avenue. Transfers to Elevated and Subway lines will be issued on request and upon payment of established fairs, by operators of both street cars and buses. Transfers are valid only when presented within time limits and in accordance with regulations printed on the back theecof.
TRANSFERS
Transfers are permitted between Chicago Rapid Transit Company subway and elevated trains and streetcars and buses operated by the Chicago service lines, or between subways and elevated trains and buses of the Chicago motor coach company. Transfers are valid at elevated or subway transfer stations where lines of the Chicago Rapid Company cross, intersect, connect with, converge with or diverge from such street car or motor coach lines. Subway, Elevated, street car and motor coach routes are shown in detail on this map. Transfers are issued ON REQUEST AND AT THE TIME FARE IS PAID by all Subway and Elevated ticket agents on the Rapid Transit System south of Howard Street and next of Desplaines Avenue. Transfers to Elevated and Subway lines will be issued on request and upon payment of established fairs, by operators of both street cars and buses. Transfers are valid only when presented within time limits and in accordance with regulations printed on the back theecof.
This is a map for the rapid transit lines in the Chicago “L” in the 1940’s. From http://www.wbez.org/blogs/john-r-schmidt/2012-06/how-chicago-l-grew-99584