West Chicago Street Railway 4 while at South Shops.
While this car is painted as West Chicago Street Railway 4, its history is interesting. Per the Preserved North American Electric Cars Roster:
North Chicago Street Railroad #922 1895-1899
Chicago Union Traction #4022 1899-1908
Chicago Railways #4022 1908-1914
Chicago Surface Lines #4022 1914-1933
Rebuilt as "West Chicago Street Railway #4" in 1933 for display at the 1934 World’s Fair.