More Than Somewhat (1937). This quotation is associated with Runyon, but the Chicago Tribune, 10 May 1936, printed the following: "'The race is not always to the swift, nor the battle to the strong, but that is the way to bet,' as Hugh Keough used to say." Keough was a Chicago journalist.
Will Rogers, Bryan B. Sterling (1995). “Will Rogers Speaks: Over 1,000 Timeless Quotations for Public Speakers (writers, Politicians, Comedians, Browsers ...)”, M Evans & Company