Saint Paul Union Depot is an historic railroad station and intermodal transit hub of the city of Saint Paul, Minnesota, United States. It currently serves inter-city rail, inter-city bus, and local bus services. METRO Green Line also serves Union Depot, through a station outside the headhouse.At one time the Saint Paul Union Depot Company controlled 9.24 miles (14.87 km) of St. Paul trackage and terminal facilities, including the depot building.