Hanford MacNider was born on October 2, 1889, in Mason City, Iowa. He was the son of Charles Henry McNider, a banker, and May Elizabeth Hanford.
Until his teenage years, he used the name McNider. When it was discovered that his grandfather had dropped the "a, " his father, who was unable to change his own name because of legal complications, insisted that Hanford return to the original spelling.
The son of Mason City's most prominent citizen, MacNider spent summers sailing and fishing and learned to use his fists at an early age to defend himself from local toughs.