Hyde was born on July 12, 1877, in Princeton, Missouri, the son of Caroline Emity Mastick and Ira B. Hyde. He also had two older half-brothers by his father's previous marriage. Ira Hyde, a native of New York state and an alumnus of Oberlin College, had practiced law in Minnesota and Washington, D. C. , before settling in Missouri in 1866. He was a Union Army veteran and served as Republican congressman from the state's Tenth District in 1873-1875. From his parents, both of colonial Massachusetts descent, Arthur presumably acquired his conservative and puritanical bent. Since Arthur's mother died when he was twelve, he was particularly influenced by his father.