High Quality Content by WIKIPEDIA articles! Union Station is a major railroad station which opened in 1925 in Chicago, replacing an earlier 1881 station. It is now the only intercity rail terminal in Chicago, as well as being the city`s primary terminal for commuter trains. The station stands on the west side of the Chicago River between Adams Street and Jackson Street, just outside the Chicago Loop. Including approach and storage tracks, it is about nine and a half city blocks in size. Its facilities are mostly underground, buried almost entirely beneath streets and skyscrapers.