Quote:
...Anyone know more about the Rwy. Postal Car Exhibit at the Fair?...
I am still searching for a an image of the Postal Car Exhibit. I do own this postcard, it show the Burlington RPO and was a part of the railroad section of the Fair.

Here is another card which shows the railroad section of the fair, but was the postal car exhibit located here? I suspect it was as shown here

The railroad section of the Fair was located here

But the remaining question is were cancels being applied at the Postal Car Exhibit or were they applied at the special fair Philatelic Agency building?
The Century of Progress commemorative stamps were first issued a few days before the official fair opening (sold starting May 25, 1933 at the main post office at Chicago, Ill.). The Fair and Philatelic Agency officially opened on May 27.
An interesting "Fair fact", shortly after opening (between June to November) there was an outbreak of amoebic dysentery at the Fair. Over 1000 cases were reported and almost 100 people actually died. A guy named Joel Connolly, who worked for the Chicago Bureau of Sanitary Engineering, finally resolved the problem and ended the outbreak.
He overcovered 'defective plumbing' that was permitting sewage to contaminate the drinking water in two hotels. Yikes!
Don