Flanagan was born in 1893 in Clinton, Iowa; graduated in 1913 from Grinnell College in Grinnell, Iowa; and later studied at the Palmer College of Chiropractic in Davenport, Iowa, during the 1920s.[2] After college, he worked in Fond du Lac, Wisconsin, and Chicago.[2] He served with the medical detachment of the 33rd Infantry Division during World War I.[2]
Flanagan first broadcast sports for WOC in Davenport in 1921,[3] getting his start as a fill-in announcer.[2] He joined WBBM in Chicago in 1927, and became their first baseball announcer.[2] He served as the radio announcer of Chicago Cubs games from 1929 to 1943,[4] and also announced Chicago White Sox games.[5] While home games in Chicago were broadcast live, Flanagan recreated the play-by-play for road games from reports transmitted by ticker tape.[5]
In 1933, Flanagan served as radio announcer for the first Major League Baseball All-Star Game, held at Comiskey Park.[6] He also did the play-by-play for three World Series (1932, 1934, and 1938) for CBS Radio.[6] In his final season of announcing for the Cubs, 1943, he was assisted by Bert Wilson, who took over the lead role in 1944.[7]
Flanagan died in 1963 in Scottsdale, Arizona.[3] At the time of his death, he was the sports director for KOOL in Phoenix, Arizona.[3] Flanagan has twice been a finalist for the Ford C. Frick Award, presented by the National Baseball Hall of Fame.[8][9]