I found this under the B&O section of George Elwood's Fallen Flags site, but it is actually CB&Q's ceremonial 4-4-0 35. I don't remember seeing this engine under steam as a showpiece before. It was refurbished in the joint CB&Q/C&S shops in Denver in the early 1930s, but in other photos of it that I have seen, it appears cold. Anyone know what event this might have been? The 1948-49 Chicago RR Fair maybe?

http://www.rr-fallenflags.org/bo/bo-s35.jpg