The Postal Service has asked customers to place stamps in the upper-right corner of envelopes and other mailings for years. Do you know why?

When postage stamps were first introduced in 1847, they were hand-cancelled individually by Postmasters and postal clerks.

The introduction of high-speed cancelling machines in the 1890s changed things.

“[T]he placement of stamps in the upper-right corner became more important to be as efficient as possible,” Daniel Piazza, chief curator of philately at the National Postal Museum, told the science and history site Mental Floss recently.

The right-hand corner also was chosen because most mail handlers are dominantly right-handed.

Although the position of the stamp is not critical, customers will save themselves delivery time by placing the stamp in the right spot.

“Your letter wouldn’t be thrown out if you didn’t follow the guidelines,” said Sue Brennan, a senior public relations representative. “But using them could speed up the processing and subsequent delivery.”

Source: USPS News Link