The remaining four original companies used the station when it opened in 1881. The headhouse of the Union Depot, a narrow building, fronted onto Canal Street and stretched from Madison Street to Adams Street. Tracks led into the station from the south, and platforms occupied a strip of land between the back of the headhouse and the bank of the Chicago River. South of the station, Adams, Jackson, and Van Buren Streets rose over the tracks and the river on bridges. The station, along with its successor, was effectively two back-to-back stub-end terminals. Virtually all trains arriving would terminate there, and passengers traveling further would need to change trains.