Jackson 144 E. Jackson Blvd.
16th Street 1618 S. Prairie Ave.
31st Street
51st Street 5001 S. Lake Park Ave.
Brookdale 6921 S. Kenwood Ave.
Burnside 803 E. 95th St.
Front Street 11630 S. Front St.
Riverdale 14101 S. Highlawn Ave.
Harvey 15739 West Ave.
Homewood 18100 S. Park Ave.
Vollmer Road 2850 W. Vollmer Rd.
Matteson 3700 W. 219th St.
University Park 4500 W. Stuenkel Rd.
Cheltenham 2950 E. 80th St.
Laflin Street 1500 W. 123rd St.
Substations constructed for the original 1926 electrification were 16th Street, Brookdale, Front Street, Harvey, Vollmer Road, Cheltenham, Laflin Street.
In the early 1970's, the Matteson substation was added, in anticipation of the new air conditioned Highliner cars entering service, increasing the demand for electricity. With the 1977 extension to University Park, a new substation was added there. And in the early 1980's, the Jackson substation was added, in anticipation of new air conditioned cars entering service on the South Shore Line/NICTD, further increasing the demand for electricity.
And with new cars entering service during the 2000's, with greater electrical requirements, Metra announced plans to further increase the electrical capacity. A new substation would be constructed at 31st Street. And the four tie stations (51st Street, Burnside, Riverdale, Homewood) would be replaced with new substations. Tie stations had been established midway between certain substations, as locations where sections of electrification could be electrically separated. But in the event of a substation failure, the separate sections of electrification could in an emergency be "tied" or "jumped" at the tie station, allowing a section to receive electricity from another substation.
As of 2014, this substation program was in the planning and funding stages.