A new TV ad for the United Negro College Fund claims that African Americans invented the traffic light and the mailbox. It's true!
There were public collection boxes earlier, but mail wasn't widely delivered to homes until about 1890, and in 1892 George E. Becket, from Providence, R.I., was granted patent #483,525 for "the house-door letter box," the mail slot with the receptacle behind it. In fact, this is a twofer: the street letter drop mailbox with a hinged door that closes to protect the mail was patented in 1891 by another African American inventor, Philip B. Downing (US Patent # 462,096).
There were a couple of primitive precursors of the traffic light, but
[W]e have Garrett Augustus Morgan to thank for the modern version and first patent of this traffic-stopping invention.
The son of former slaves, Morgan was born in 1877 in Kentucky. He later moved to Cincinnati and then Cleveland, where he owned and operated a sewing-machine repair business and earned quite a reputation as a technician. A multi-talented businessman, Morgan went on to establish the newspaper The Cleveland Call.
In early 20th century Cleveland, as in other major U.S. cities, the roads were clogged with pedestrians, bicycles, animal-drawn wagons, and those newfangled automobiles. There were no traffic laws to speak of, and chaos ruled the streets. Accidents were frequent. After witnessing one such traffic accident, Morgan felt compelled to improve the situation. The result? The precursor to the modern traffic signal, patented on November 23, 1923.