Mill Creek Valley was a historic neighborhood located in the central corridor between 20th Street and Saint Louis University in St. Louis, Missouri. European settlement began in the 18th century with mills established along La Petite Rivière, now known as Mill Creek. It became an industrial and railroad center in the 19th century. Union Station was opened in 1894. The building was closed in 1978 and renovated for commercial use. Also a residential and commercial center, Mill Creek Valley was populated by German immigrants and African Americans, before and after the Civil War. More people moved into the area during World War II to support the war effort.