miller was born in clarinda, iowa. his parents were mattie lou (née cavender) and lewis elmer miller. in 1915, miller's family moved to grant city, missouri, and he started playing in the town orchestra. at first, he played cornet and mandolin, but he switched to trombone by 1916. in 1918, the miller family moved to fort morgan, colorado, where miller went to high school. during his senior year, he started a band with some classmates. they played "dance band music". by the time miller graduated from high school in 1921, he had decided to become a professional musician.