In 1928, the District [the Sanitary District of Chicago, known today as the Metropolitan Water Reclamation District of Greater Chicago] built its own railroad to haul dried sludge from its West Side Sewage Treatment Works at 4200 South Laramie Avenue to its sludge dump at 5000 South Harlem Avenue. CSDX is the reporting mark for the District’s local Short Line railroad, and CSDX 39 identifies a former District sludge dump car. The car was built by the Western Wheeled Scraper Company of Aurora, Illinois, in 1930.
The District observed its centennial in 1989 and donation of the rail car in 1990 to the Illinois Railway Museum recognized a significant part of District operations in serving the public.
Read my article on "CSDX39 and the History of the Sludge Express" in Issue 255 of Rail & Wire (Summer 208), starting on p. 24.