Al and Dave, I might have to rain on this parade. I didn't notice right off that the Cincinnati pennant says "Redlegs", the Reds only used that name from 1953-1958. I also found this auction (don't know the seller, and not trying to "out" anything)
http://www.ebay.com/itm/1950s-Baseba...item4abb892f88
It shows the identical pennants that Al posted. (note the arrow on the Indians), and includes the Brooklyn Dodgers. This would date them as 1957 or earlier. Its possible Fleer used old pennants, but 6 or more years older?
I don't think we're done yet, sorry Al. Randy