Chicago's first elevated trains were hauled by steam locomotives. The Lake Street Elevated Railroad's steam locomotives were 0-4-4T's built by the Rhode Island Locomotive Works. #9, the "Charles H.", was a typical such locomotive. On September 30, 1997, locomotive was displayed in downtown Chicago in commemoration of the CTA's 50th anniversary. Locomotive is on permanent display at the St. Louis Museum of Transportation.
Between 1922 and 1924, the Chicago Rapid Transit Company acquired 205 steel cars, numbers 4251-4455. Cars 4271 and 4272 have been preserved by the CTA in their original paint scheme, and were operated around the Loop on October 12, 1997, in commemoration of the Loop's 100th anniversary.
The 4000 series cars remained in service until 1973, when the overhead trolley wire on the Evanston route was replaced with third rail. Car 4451, painted in the CTA scheme, is preserved at the Fox River Trolley Museum in South Elgin, IL.