Croton-on-Hudson Gets Hyphenated, April 1, 1948 Sixty-nine years before the publication date, on April 1, 1948, the U.S. Postal Service officially incorporated hyphens into the cancellation stamp for what had previously been called "Croton on Hudson." This transition is documented through a pair of commemorative envelopes known as "last/first covers," which were inscribed by Augustus W. Dymes, Jr…