There was a “limousine/taxi” transfer service for passengers between the various Chicago stations, I believe with the blessings of the railroads.
It was called the Parmelee Transfer Company. Founded in 1853, and at some point became the “official” transfer service between Chicago stations. Interline tickets included Parmelee coupons if a transfer of stations was required. I’m not sure whether Parmelee carried checked baggage between stations, or if the railroads used their own vehicles. I believe Parmelee transfer service ceased to be provided with through tickets some time in the 1950’s. Parmelee is still in business under the name Continental Airport Express and the Parmelee family still appears to be associated with it.
Checker apparently controlled Parmelee at one point but relations seem to have been complicated and changed a lot, involving Yellow Cab (which was related to Hertz).
Checker made special vehicles for the Parmalee service, larger than their cabs, with greater luggage capacity.
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