Robert M. Riddle was born in 1812, the son of Judge James Riddle. He entered the mercantile trade in
Pittsburgh in the firm of Riddle and Forsyth, and subsequently engaged in the banking business in
Philadelphia. In 1837, he became editor of the
Advocate, a
Whig newspaper in Pittsburgh. He served as the city's
postmaster from 1841 to 1845. When his term of office expired, he took over the paper called the
Spirit of the Age, and renamed it the
Commercial Journal. He was connected to the paper as editor and proprietor until failing health near the end of his life forced him to retire from it. While at the helm of the
Journal, Riddle was elected on the Whig ticket as
Mayor of Pittsburgh. and was active in pushing an anti-slavery agenda within that organization. He ended up a
Republican. ==Death and interment==