Philip B. Downing is known for a number of patents, including the street letter box in 1890, the precursor to the modern postal box. Downing's design featured a simple, four-legged box with a hinged metal door for sending outgoing mail. This invention simplified the mail process for many people.
Philip Downing's street letter box influenced and expanded the mail system in the United States. He also patented an electrical railroad switch that allowed workers to power off specific trains when needed. His design influenced later inventors who created electrical switches capable of controlling lights in buildings such as houses and offices.