Rare pony express envelope bound for Vermont to be auctioned in New York City

A rare envelope from the 1860s, the only one ever sent to Vermont via the fabled Pony Express, is going up for auction this month.

Bids will start at $2,500, but it's anyone's guess how high the price might go.

Or who sent the letter, which is long gone.

The Pony Express was only in operation from April 3, 1860, to Oct. 26, 1861. It was "by far the most effective way to communicate cross-country," operating horse and rider relay teams, according to the US Postal Service.

H.R. Harmer Fine Stamp Auctions, which is handling the sale of the Vermont piece, said only about 250 envelopes were carried by the Pony Express before it shuttered.

The Vermont envelope is postmarked October 5, 1861, and was sent to John H. Lyons in the town of Colchester, which is in northern Vermont bordering Lake Champlain, a news release from the auction house states.

"He was the son of a very prominent farmer in the area," auction house CEO Charles Epting told affiliate WCAX of Lyons.