In 1891, anyone interested in mailing a letter would have to make the long trip to the post office. Philip B. Downing designed a metal box with four legs which he patented on October 27, 1891. He called his device a street letter box and it is the predecessor of today’s mailbox.
One year earlier, Downing patented an electrical switch for railroads which allowed railroad workers to supply or shut off power to trains at appropriate times. Based on this design, innovators would later create electrical switches such as light switches used in the home.
article found at Blackinventors.com