Poster stamps are a subset of Cinderella stamps. A Cinderella stamp is essentially any stamp not produced by a government for use as postage, a definition which includes (to some people) officially-issued stamps such as tax stamps, telegraph stamps and locals. Poster stamps are advertising stamps, and usually poster-like in their appearance. Many are indeed just reduced versions of actual posters, and were issued in conjunction with the events for which the posters were produced. The poster stamps on this page were all issued in conjunction with the Chemical Industries Exposition in the U.S., now called "Chem Show". One even thas a train, one of my favorite stamp topics! Below are images of all I have been able to accumulate so far, plus others contributed from other collectors. Thanks to the history page of the organization that runs the show, I was able at last to assign reliable dates to the first two. 10/31/17 - Collector Peter Zecevic sent me images of four new stamps - 1920, 1951(2), 1959, and 1969! Thanks, Peter. His additions suggest there are at least seven more - 1918, 1919, 1949, 1955, 1957, 1965, and 1967 - plus more post-1969? 11/13/18 - Collector Ken Collins sent me two new entries - a stamp for the Fifth show, 1919, and one for 1973, plus some varieties and ephemera, all shown below. Thanks, Ken. Again, this expands the number of potential entries in this catalog. Can anyone else add to the exhibit below?

Images in the main part of this page are NOT shown in exact relative sizes. Above: Image of the labels for shows 1-16, scanned together and at the same scale (no stamp has been found for show #4). All stamps from #13 onward are the same size.

Statistics about the series.

SIZES given below are for the image/vignette only - borders can vary.

FIRST 1915 week of Sept. 20 Size: 40x61mm

SECOND 1916 week of Sept. 25 Size: 40x63mm

THIRD 1917 week of Sept. 24 Size: 44x62mm

FOURTH 1918 week of Sept. 23     NOT SEEN We know the Expo was held in 1918 - see tickets below - but I have seen no stamp.

FIFTH 1919 week of Sept. 22 - Chicago Size: 47x62mm

SIXTH 1920 week of Sept. 20 Size: 47x62mm

Below are three tickets, images courtesy of Ken Collins - two different ones for 1918, and one for 1920.

SEVENTH 1921 Sept 12-17 Size: 47x67mm

EIGHTH 1922 Sept 11-16 Size: 47x67mm

NINTH 1923 Sept 17-22 Size: 49x66.5mm

TENTH 1925 Sept 28 - Oct 23 Size: 46x68mm

TENTH 1925 Sept 28 - Oct 23 Size: 46x68mm missing color version

ELEVENTH 1927 Sept 26 - Oct 1 Size: 33x54mm MAJOR SIZE REDUCTION

From 1915 though 1923, the shows were held every year. After 1923 they were held every two years. --------------------- Below, the 1921 stamp used on cover, and a pair of the 1922 stamp with selvage on both sides, telling us that this was issued in strips. An odd format, it seems to me. Based on the stamps he has seen, and the changes to stamp dimensions, Ken Collins thinks that this two-abreast format was used for Shows 1 thru 10, so no stamp from that period is found with a straight edge.     Next: - an ad for the 1922 show from the "Journal of Industrial & Engineering Chemistry", - a show cancel for 1923, - and a block of ten (2x5) of the 1927 stamp with selvage on three sides. The height (in stamps) of the sheet is unknown, but probably 4x5 or 5x5. In any case, no individual stamp should be found with a straight edge.     ARE THERE OTHER SHOW CANCELS? Can anyone provide scans of full sheets or large multiples of any of the stamps above? Note that the 1929 stamp for show 12, immediately below, has one straight-edge, as do many of the others from here on, yet the stamp vignette has the same dimensions as the stamp for show 11. So did it have the same printing format as #11 - 5 wide - or the 4x4 layout shown farther down, with outer edges imperf?

TWELFTH 1929 May 6-11 Size: 33x54mm

THIRTEENTH 1931 May 4-9 Size: 35x51mm

FOURTEENTH 1933-1 Feb 27 - Mar 4 Size: 35x51mm

FOURTEENTH 1933-2 Dec 4-9 Size: 35x51mm

FIFTEENTH 1935 Dec 2-7 Size: 35x51mm

SIXTEENTH 1937 Dec 6-11 Size: 35x51mm

Note the TWO shows in 1933 (both numbered 14th), and the change from Spring back to Fall dates from then on. Below: - a postcard with the poster image for the 1933 show! - two varieties of the 1935 stamp - one that looks imperforate (but might be simply a trim-job), another without the "SEE OUR EXHIBIT" lettering in white at the top - a block of 8 of the 1937 stamp with a vendor overprint.         ARE THERE OTHER SHOW POSTCARDS? Note the straight-edges on both sides of the 1937 block. The sheets must have transitioned from the 5 abreast with surrounding blank selvage, as shown on the 1927 block of ten, to the 4x4 format with all the straight edges somewhere between the 11th show and the 16th show. The 4x4 with straight edge format seems to be continued to the 29th show sheets. (Thanks to Ken Collins for this analysis)

SIXTEENTH 1937 Dec 6-11 Size: 35x51mm With vendor overprint The only such overprint I have seen

SEVENTEENTH 1939 Dec 4-9 Size: 35x51mm

EIGHTEENTH 1941 Dec 1-6 Size: 35x51mm

NINETEENTH 1943 Dec 6-11 Size: 35x51mm

TWENTIETH 1946 Feb 25 - Mar 2 Size: 35x51mm

TWENTY-FIRST 1947 Dec 1-6 Size: 35x51mm

WWII didn't stop the shows, but the 1945 show was delayed a year. The 1947 show was back on schedule, an odd-numbered year. Below, a full sheet of the 1943 stamp, 4 by 4, imperf on the outer edges. It looks like this format was initiated in 1929, so from then on it can be a challenge to find stamps with perfs on all four sides.

TWENTY-SECOND 1949       NOT SEEN

TWENTY-THIRD 1951 Nov 26 - Dec 1 Size: 35x51mm

TWENTY-THIRD (2) 1951-2 Nov 26 - Dec 1 Size: 35x51mm 10/31/17 - NEW FIND WHY TWO VERSIONS?

TWENTY-FOURTH 1953 Nov 30 - Dec 5 Size: 35x51mm

TWENTY-FOURTH (2) 1953-2 Nov 30 - Dec 5 Size: 35x51mm 9/27/17 - NEW FIND WHY TWO VERSIONS?

TWENTY-FIFTH 1955       NOT SEEN

Note that the 1953 show was held in Philadelphia - Why the change? Most other years were in New York. I see that Grand Central Palace, the venue for all prior years except 1919 & 1943, closed in 1953, so that must have prompted the move. By 1959 the show was back in New York, at the New York Coliseum. The Chem Show web site says "... with the exception of three shows in Chicago and one in Philadelphia, every Chem Show ... has been in New York City." The only stamp shown here that says "Chicago" is the one for 1919. The tickets for 1918 say New York. So when were the other two in Chicago? Below, a set of progressive proofs of the 1951 stamp, which suggests to me that there were some philatelists lurking among the chemists. AND another full sheet, this time of the 1963 stamp, still 4x4, outer edges imperf.

TWENTY-SIXTH 1957       NOT SEEN

TWENTY-SEVENTH 1959 Nov 30 - Dec 4 Size: 35x51mm

TWENTY-EIGHTH 1961 Nov 27 - Dec 1 Size: 35x51mm

TWENTY-NINTH 1963 Dec 2-6 Size: 35x51mm

THIRTIETH 1965       NOT SEEN

THIRTY-FIRST 1967       NOT SEEN

THIRTY-SECOND 1969 Dec 1-5 Size: 35x51mm

THIRTY-THIRD 1971       NOT SEEN

THIRTY-FOURTH 1973 Nov 26-30 Size: 35x51mm Imperf - probably peel & stick - was this the new format?

I find it interesting that even as late as 1963, the Exposition was still showing factories belching polluted smoke into the air.
Note that the 1969 stamp still shows the factories, but no smoke!
Was this a sign of environmental awareness? (The EPA was established in 1970)