incoming 1815 folded letter with "Washn. City Sep 29" datestamp, franked "Sup't Gen'l Office" and handstamped "Free", addressed to Matthew Irwin, Esq., docketing indicates the letter was received July 28, 1816 (10 months after it was sent), extremely fine, the earliest recorded piece of mail to or from Green Bay, six years before a post office was established, an extraordinarily rare cover, ex-Valentine