Quote:
That was my original assumption but my search trying to associate it to a specific stamp said usps never used that number and reference it to a British #.
That underscores the issues with AI searches. While its answer was correct, it was misleading. Specifically the USPS did not use the number for a plate. On the other hand, as you later learned, the USPOD and BEP did use the number.
The USSS' Durland Plate Number Guide also list plate numbers used by
stamp issue Scott number.