Parts of the route use an abandoned railroad right of way, an abandoned railroad tunnel through central St. Louis, and the Eads Bridge over the Mississippi River. The original route from the airport through downtown St. Louis to East St. Louis, Illinois, opened in 1993. It was extended from East St. Louis to Belleville in May 2001.
Further extensions are now under construction or in the planning stage.
Cross County Metrolink , official project site for a Metrolink extension which is to begin construction in 2002. Metrolink - St. Clair County , official project site for a Metrolink extension into Illinois whose first section opened in May 2001. The Eads Bridge over the Mississippi River. A westbound train runs on the viaduct across the Mississippi River flatlands, on the east side of the river in East St. Louis, Illinois. Metrolink operates on the former Wabash Railroad right of way in Forest Park, west of St. Louis.