Experienced collectors looking for early cards of postwar stars have often been led to cards released just after the Second World War. Two such series that are well-known were made by Sports Exchange, an early hobby outlet that issued its own “Trading Post” periodical from 1945-1950. Burdick classified the sets as W602 (small cards, called “Miniatures” in the hobby literature) and W603 (two forms of large cards, one a full sheet and one a half-sheet).
Since the W602-603 issues were catalogued, a few facts have emerged. The cards were issued in series starting in 1946 and going into 1949. In keeping with Burdick’s sometimes idiosyncratic and confusing approach to organizing sets for the ACC (for example, the early Goudey cards issued under its Oh Boy Gum brand are catalogued as E282 rather than under an R designation), the large cards were numbered 603 and the small cards were numbered 602 even though the first series of the large cards was issued first. The cards were sold in sets by mail order independently of the periodical itself. Here is a ‘teaser’ advertisement for the first set of W603 cards that ran in the August 1946 issue of Trading Post:
In the November 1946 issue, Sports Exchange ran a two-page spread promoting the first series of W603:
The W602-W603 issues are best known for having a 1947 Warren Spahn, which is one of a few 1947 Spahn cards that predate the 1948 Bowman and is gaining wider acceptance as a true rookie card.
They’re somewhat scarce with only a few dozen usually found on eBay at any given time.
What was unknown (and until now uncatalogued) is that the Sports Exchange baseball cards followed an earlier, short-lived pin-up series that the company created in 1946 and ran in the Trading Post itself.
This is in keeping with a long history of in-publication premiums from The Police Gazette in the early 20th century to the numerous sets of newspaper card issues of the 1930s. The Trading Post set debuted in April 1946, as advertised on the front cover of the periodical:
The first player featured was a really good one, Stan Musial:
The Musial picture was printed on a full page (approximately 6 x 9) on the same news stock as the rest of the periodical and is designated “Exchange Photo No. 1”. Beginning the next month with Bob Feller, the premiums were printed on a higher-quality whiter stock and called “Exchange Photo Album” without numbers.
The format of the pictures remained the same for the rest of the run, which was short. The last picture was issued in the November 1946 magazine and pictured Joe DiMaggio.
We know that Stan The Man kicked off the series and that The Yankee Clipper closed it, because the December 1946 issue of Trading Post did not have a pin-up in it.
My guess is that the company had success with the W603 cards and decided it would be counter-productive to give away free cards when it could sell them instead. Consequently, all of the pin-up pictures are in Volume 2 (1946) and the set is very likely complete at 8 pin-ups, assuming that all issues in 1946 have pin-ups. We cannot be sure of that. The Trading Post periodical itself is very difficult to locate, so the pin-up checklist is incomplete. 
Here is what we have so far:
Vol. 2 #3 April Stan Musial
Vol. 2 #4 May Bob Feller
Vol. 2 #6 July Hal Newhouser
Vol. 2 #7 August Hank Borowy
Vol. 2 #8 September Mel Ott
Vol. 2 #10 November Joe DiMaggio
If anyone can fill in the missing links in the checklist, please contact me via the email address in my bio below.
The significance of this uncatalogued issue is readily apparent: these are very early postwar issues of the best players of the era (and Hank Borowy…). The April 1946 pin-up of Musial is his earliest verifiable domestic major league issue and may even predate the 1946 Propagandas Montiel Musial issued in Cuba, depending on when in 1946 the latter card was released.
Thanks to David Kathman for his help with the checklist and Trading Post periodical background.
