The Answer:

First, some background. In the early 1800's, most letters in the U.S. were taken to the post office to be mailed, and recipients had to retrieve their mail from the post office. It wasn't until 1863 that mail was delivered to homes of people who lived in cities without additional charge. By 1890, hundreds of cities delivered mail to residents' homes, thus leading to a need for mailboxes.

While not the earliest, in 1892, George E. Becket, of Providence, R.I., was granted a patent for his "house-door letter-box," an improved mail slot that was permanently mounted on the front door of a house.

The first letter box (where the public could leave its letters) sanctioned by the United States Postal Service was patented on March 9, 1858 by Albert Potts. His design incorporated the lampposts that his company made with a letter box. His receptacle was rather small and required frequent emptying. It was not the first in history, however; that honor goes to Renouard De Valayer. In 1653, he set up a short-lived postal system using collection boxes on street corners around Paris.

—The Editors