Gus Spector is a member of the Pennsylvania Historical Society, the Atwater Kent Museum, and the American Philatelic Society and has been a prodigious collector of Philadelphia postcards for more than 35 years. His interests in Philadelphia lie in the 19th- and 20th-century history of its people and places. He is the author of Philadelphia: Historic Exteriors and Interiors, Center City Philadelphia, and Philadelphia Neighborhoods.