In a first-ever release, the U.S. Postal Service issued a pane of 50 stamps, with each stamp in the pane depicting the flag of one of the states of the union. Panes of commemorative stamps, in the "traditional" stamp size, normally contain 50 stamps. Thus, while the pane was standard, the subject matter was rather unique. The flags are arranged in the order of entry of the states to the union, with the first 13 being the original colonies in the order in which they ratified the U.S. Constitution. The remaining 37 are ordered on the basis of their approval by the U.S. Congress for admission to the union. This set of stamps was quite popular for display purposes as well as for the more traditional addition to stamp collections.