Existing comment:
Both Great Britain and France had used trains as rolling post offices for years before the first documented en route mail sorting in the US, in July 1862. Specially-outfitted cars contained the paraphernalia needed to collect, postmark, sort, and re-pouch the mail, from handstamps to pigeonholes. After WWII, Highway Post Offices (HPOs) inside special buses supplemented the RPOs. Ultimately, the RPO system outlasted HPOs by three years.
Trains on stamps are a popular collecting topic, both with stamp collectors and with railroad history buffs. |