I was really lucky and recently acquired a Hafner "Century of Progress" windup train set. It runs great and what really amazed me was a battery powered headlight and tail light that uses 2 AA batteries. I believe the set was sold from 1933 - 1935 (I didn't realize that AA batteries were in use at that time!). Since Hafner manufactured windup trains in Chicago, then a special set would make sense for the "Century of Progress" World's Fair in 1933 that took place in Chicago.