The new stamps also made correspondence far more convenient. Previously, letters of one or more sheets had been folded up, sealed shut with wax or an adhesive wafer, addressed on the “cover” side, and taken to a post office. The postmaster calculated the postage and jotted it on a corner of the cover, perhaps adding the date and name of his town or office. . . .

Most of the time, however, the cost was paid by the recipient, who had to come to the post office to fetch it. He or she might well decide that, unless it was a love letter, the message wasn’t worth the expense and return it to the postmaster. This labor-intensive system naturally generated a huge backlog of unwanted mail and dead letters. In one of many schemes to avoid postage, a traveler promised loved ones that he or she would send a letter upon reaching a particular destination; when it arrived, the reassured recipients would refuse it. Indeed, Zachary Taylor did not realize that the Whigs had nominated him to be their presidential candidate in 1848 because their letter to that effect sat in his local post office amid a pile of mail that he had refused to redeem.

Stamps revolutionized this cumbersome mailing process. Postage was standardized and prepaid by the sender, so recipients were no longer primed to reject all but the most important letters. (As a result, the volume of commercial solicitations, advertisements, religious tracts, and get-rich-quick promotions soared along with that of personal correspondence.) Moreover, stamps came in sheets that, although not yet perforated, were conveniently backed with adhesive and ready to stick on covers, which themselves were soon rendered obsolete by manufactured envelopes.