He was the eldest child of Cornelius Covenhoven Van Horne (1794–1854) by his second wife Mary Minier Richards of Sandusky, Ohio. Cornelius studied law at Union College, but took his family out west to seek his fortune farming. Misfortune followed as his house, barns and law books were destroyed by fire, and his first wife died shortly afterwards. Abandoning farming, he returned to the law and became Recorder of Will County, Illinois, moving his family to Joliet, Illinois. Cornelius was active in getting the city its first charter, and because of this he was elected Joliet's first mayor. When the city later built a new bridge it was named the Van Horne Bridge.