Career
Southgate was a student and expert of the Bureau Issues of the United States. In addition to participating in philatelic activities in the Washington, District of Columbia At the Bureau Issues Association (now the United States Stamp Society) he was its first president and chairman of the board (1939–1940). Southgate was also active in the American Philatelic Society and was one of the first to investigate and study the archives of the Bureau of Engraving and Printing.
The, also known as the Southgate Trophy, was established by the United States Stamp Society in November 1968 as its most important award for 19th century exhibiting.