March 9, 1892 - Metropolitan West Side Elevated Railroad Company incorporated.

May 6, 1895 - service begins between downtown Chicago (Canal Street) and Robey Street (now Damen Avenue) on northwest side, using electric cars.

May 17, 1895 - service begins to downtown terminal at Franklin Street, after completion of bridge over Chicago River.

May 25, 1895 - line completed northwest to Logan Square.

June 19, 1895 - Garfield Park main line completed west to Cicero Avenue.

July 29, 1895 - Humboldt Park branch completed to Lawndale Avenue.

April 28, 1896 - Douglas Park branch opens between Marshfield Avenue junction and 18th Street.

August 7, 1896 - Douglas Park branch extended to Western Avenue.

October 11, 1897 - trains start using Loop elevated line, Franklin Street terminal closed.

February 3, 1899 - company reorganized as Metropolitan West Side Elevated Railway Company.

June 16, 1902 - Douglas Park branch in service as far west as 40th Avenue (Pulaski Road).

August 25, 1902 - Garfield Park line extended west to 52nd Avenue (Laramie Avenue). On the same day, connecting interurban service inaugurated on Aurora Elgin & Chicago Railway between 52nd Avenue and Aurora.

October 3, 1904 - new downtown terminal opened at Fifth Avenue (Wells Street) and Jackson Street for rush hour trains, relieving congestion around Loop elevated.

March 11, 1905 - Aurora Elgin & Chicago trains begin using Garfield Park line to Fifth Avenue terminal. At the same time, Metropolitan Elevated Garfield Park service extended to Desplaines Avenue in Forest Park, providing local service over that AE&C ground level trackage.

May 22, 1907 - Douglas Park branch extended to 46th Avenue (Kenton Avenue).

December 16, 1907 - Douglas Park branch extended to Cicero Avenue.

August 20, 1910 - Douglas Park branch extended to 52nd Avenue (Laramie Avenue).

August 1, 1912 - Douglas Park branch extended to 56th Avenue (Central Avenue).

August 1, 1915 - Douglas Park branch extended to Lombard Avenue.

July 1, 1922 - Aurora Elgin & Chicago Railway reorganized as Chicago Aurora & Elgin Railroad.

March 16, 1924 - Douglas Park branch completed to Oak Park Avenue.

October 1, 1926 - Garfield Park line extended to Roosevelt Road in Westchester, over a new branch extending south from Chicago Aurora & Elgin line at Bellwood. Trains used CA&E main line east of Bellwood, replacing CA&E as provider of local service over this segment.

December 1, 1930 - Westchester branch extended south to 22nd Street/Mannheim Road.