An Indiana State Historical Marker for J.D. Oliver and Copshaholm was dedicated August 8, 2024. It stands on the west side of Chapin Street, near the Oliver Mansion, where J.D. lived with his wife, Anna, and their four children. A leading industrialist of his time, J.D. was president of the Oliver Chilled Plow Works. His marketing and financial acumen grew the plow business established by his father, James Oliver, into one of the largest in the world in the late 1800s. It is the sixth state historical marker to be installed in St. Joseph County in the last eight years. The marker program is administered by the Indiana Historical Bureau.