1897: Exhibition page with five specimen envelopes overprinted “UNIVERSAL POSTAL CONGRESS”, which were part of the samples given to the delegates at the 1897 Congress of Washington (5 May - 15 June), and were the stationery envelopes in use in the US from June 1897. They include 1 cent blue on buff, 2 cents green on blue, 2 cents green on amber, 4 cents red on cream and 5 cents deep blue on cream. In addition, an 1897 UPU Congress envelope used by a delegate posted to Austria showing the commemorative US flag machine cancel “WASHINGTON D.C. MAY 9 1897 CONGRÉS POSTAL UNIVERSEL”. It is franked with a 5 cents brown, which is oddly not the required colour under the UPU requirements, which stipulated blue. Fine group (6).
