James Baird Weaver was born in Dayton, Ohio, on June 12, 1833, the fifth of thirteen children of Abram Weaver and Susan Imlay Weaver. Weaver's father was a farmer, also born in Ohio, and a descendant of Revolutionary War veterans. He married Weaver's mother, who was from New Jersey, in 1824. Shortly after Weaver's birth, in 1835, the family moved to a farm nine miles north of Cassopolis, Michigan. In 1842, the family moved again to the Iowa Territory to await the opening of former Sac and Fox land to white settlement the following year. They claimed a homestead along the Chequest Creek in Davis County. Abram Weaver built a house and farmed his new land until 1848, when the family moved to Bloomfield, the county seat.