He had invested the year before in an ironworks started by two of his cousins, brothers George and Selden T. Scranton. J.H. Scranton's investment in their firm in 1846 saved the firm from bankruptcy. He later became president of Lackawanna Iron & Coal, serving until his death in 1872.

William was the oldest of six children, with two brothers and three sisters, all of whom were born after the family's move to Pennsylvania. They also had an older half-brother Joseph A. Scranton. He attended Scranton High,