1890 - Aurora Street Railway Co. incorporated to acquire horse car operation and convert to electric streetcars.
1901 - Elgin Aurora & Southern Traction Co. incorporated, acquiring Aurora Street Railway Co., Aurora & Geneva Railway Co., Aurora Yorkville & Morris Railway Co., and Elgin City Carpentersville & Aurora Railway Co.
1906 - Elgin Aurora & Southern Traction Co. merged with Aurora Elgin & Chicago Railway Co. to form Aurora Elgin & Chicago Railroad Co.
1924 - Aurora Elgin & Fox River Electric Co. incorporated to acquire former Elgin Aurora & Southern Traction Co. from Chicago Aurora & Elgin Railroad Co., which had reorganized in 1922 from Aurora Elgin & Chicago Railroad Co. Aurora Elgin & Fox River Electric Co. would be a subsidiary of Western United Gas & Electric Co.
1927 - Western United Gas & Electric Co. comes under control of Samuel Insull.
1932 - Samuel Insull resigns from Western United Gas & Electric Co.
1933 - Western United Gas & Electric Co. becomes subsidiary of Commonwealth Edison Co., Chicago's electrical utility.
1934 - conversion completed of all local streetcar operations to buses.