Born in Champaign County, Illinois, in 1881, James Sidney Mercer's first job at a newspaper was as a printer's devil (apprentice) with the St. Louis Republic. He later wrote for the St. Louis Post-Dispatch before hiring on with the St. Louis Browns as their road secretary in 1906. The following year Mercer's love for writing brought him to the staff of the New York Evening Globe. He later wrote for the New York Evening Journal, where, through syndication, his reputation gained nation-wide fame. He finally landed with Hearst's American (later Journal-American) where he stayed until his death in June of 1945.
A charter member of the Baseball Writers' Association of America, Mercer covered New York baseball with an easy, informative writing style. Ford Frick recalled: "Sid Mercer was a dedicated man. His contributions went far beyond writing. He was at one and the same time critic and defender."A recognized authority on both boxing and baseball, Mercer was appointed to the Hall of Fame Committee on Baseball Veterans less than a year before his passing.