<P> Chicago Union Station is a major railroad station that opened in 1925 in Chicago , Illinois , replacing an earlier station built in 1881 . It is the only remaining 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 West Adams Street and West Jackson Boulevard , 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 beneath streets and skyscrapers . </P>
what part of chicago is union station in
on the west side of the Chicago River between West Adams Street and West Jackson Boulevard , just outside the Chicago Loop