Term evolved from the Texas Rangers from the late 1800's meaning that it only takes ONE Texas Ranger to stop ONE riot.
The phrase was coined by Ranger Captain William "Bill" McDonald, who was sent to Dallas in 1896 to prevent the illegal heavyweight prize fight between Pete Maher and Bob Fitzsimmons that had been organized by Dan Stuart, and patronized by the eccentric "Hanging Judge" Roy Bean.According to the story, McDonald's train was met by the mayor, who asked the single Ranger where the other lawmen were. McDonald is said to have replied: "Hell! Ain't I enough? There's only one prize-fight!"
by LAHeat on Feb 13, 2014