Vanceboro is a town in Washington County, Maine, United States. The town was named after landowner William Vance. The town is located at the eastern terminus of Maine State Route 6. Vanceboro is across the St. Croix River from St. Croix, New Brunswick, Canada, to which it is connected by the Saint Croix – Vanceboro Bridge. The crossing has a 24-hour customs station managing the border. Vanceboro is also connected to St.