Amtrak usually uses a frequency or frequencies licensed to the owner of the tracks they are operating on.  See wiki page for additional frequency information.

Metra runs commuter trains on several lines. They own the Milwaukee North and West Districts, Metra Electric, Rock Island and SW Service lines. Trains operate on other railroad's tracks, including the UP-N, UP-NW and UP-W, BNSF, Heritage (CN) Corridor and North Central (CN) lines. 

Locomotives and rolling stock are owned by Metra and crews are Metra except for BNSF and UP lines.

Radio operations are on the Road channels of the various lines.

Travelers Information Stations on 1630 AM located in: University Park (Will), Naperville (Du Page), Mokena (Will), Northfield (Cook), Roselle (Du Page)

Electric commuter trains running into Chicago on track owned by Metra (Metra Electric Line) and freights on the Indiana track run by a seperate operating company.

CSS trains use the Road repeater from Kensington to Gary and Rolling Prairie to South Bend; simplex (on the repeater output) is used between Gary and Rolling Prairie.

IRM is the largest railway museum in the country, with a 5 mile demonstration railroad and many steam, diesel and electric operating items.

Operates on former Aurora, Elgin and Fox River Electric Company interurban tracks.  Also licensed for portables on 467.3125 (NFM).

 BNSF consists of lines from the former Burlington Northern and the Santa Fe railroads.

Aurora Subdivision (south) - Aurora to Savanna
Aurora Subdivision (north) - Savanna to LaCrosse
Barstow Subdivision - Galesburg to Savanna
Brookfield Subdivision - Galesburg to W. Quincy
Chicago Subdivision - Chicago Union Station to Aurora
Chillicothe Subdivision (east) - Chicago (BOCT Crossing) to Williamsfield
Chillicothe Subdivision (west) - Williamsfield to Fort Madison
Marceline Subdivision (east) - Fort Madison to Hurdland
Marceline Subdivision (west) - Hurdland to Kansas City
Mendota Subdivision - Montgomery to Galesburg

Yard repeater formerly used 151.9625 (PL 107.2) on input.

 The CN has lines in Illinois from the former Wisconsin Central, Elgin, Joliet and Eastern, Illinois Central and Grand Trunk Western.

 CP Rail has lines in Illinois from the former Soo Line, Milwaukee Road and Iowa, Chicago and Eastern/Dakota, Minnesota and Eastern.

CSX has lines in Illinois from the former BO, CO, BOCT, Conrail and Rock Island railroads. Most are concentrated in the Chicago Terminal area.

CSX trains between Chicago and Woodland operate over Union Pacific trackage to reach the Woodland Subdivision (ex-C&EI).

RA Dispatcher:
Barr Subdivision - Blue Island to Willow Creek, IN
Chicago Heights Subdivision - Harvey to Glenwood
Elsdon Subdivision - Elsdon to Munster, IN (ex-GTW)
Lake Subdivision - East Chicago area
Porter Branch - Blue Island to Porter, IN

RB Dispatcher:
Altenheim Subdivision - Forest Park to North Lawndale
Blue Island Subdivision - North Lawndale to Blue Island
New Rock Subdivision - Joliet to Henry (ex-Rock Island)

 KCS runs former Gateway Western/CMNW track from Springfield west to Roodhouse and then to Kansas City and St. Louis.

Norfolk Southern consists of lines from the former Norfolk and Western, Southern and Conrail railroads.

The former Southern Railway systemwide standard of 160.950 Road and 160.830 (Train to Dispatcher) / 160.245 (Dispatcher to Train) is being phased out in favor of a new plan where each dispatcher desk has a dedicated road channel ("Channel 1") and a dedicated dispatcher channel ("Channel 2") for all subdivisions controlled by that dispatcher desk.

 The Union Pacific has lines in Illinois from the former Chicago and North Western, Missouri Pacific and Cotton Belt railroads.

Former C&NW Lines:
Geneva East Subdivision
Belvidere Subdivision
Troy Grove Subdivision
Adams Subdivision
Rockwell Subdivision
Milwaukee Subdivision
Kenosha Subdivision
Geneva West Subdivision
Peoria Subdivision
Harvard Subdivision
McHenry Subdivision

Union Pacific Railroad Police reportedly using Motorola's WAVE push-to-talk app for communications.  Previously reported using Diga-Talk talkgroup 1047. (3/24)

Between Near West Side and North Lawndale.

Ex-C&NW yard

Closed in 2019, G3 reopened in 2021

The Belt Railway Company of Chicago is a switching and terminal railroad which is co-owned by and handled interchnge services for BNSF, CN, CP, CSX, NS and UP. BRC also serves many local customers itself.

The mainline runs south 10 miles from a connection with the Metra Milwaukee District West Line at Cragin to 67th Street (the east end of Clearing Yard), where it swings east and proceeds another 14 miles to South Chicago.

The major yard on the line is Clearing Yard, located just south of Midway Airport.

The Chicago Junction Railroad is a switching road which serves the Elk Grove Village Industrial Park. It connects with CN, CP, CSX, NS and UP.

Chicago Rail Link is a shortline and terminal railroad in and around Chicago. The ex-Rock Island main line runs from a connection with BNSF at Western Ave southwest through Gresham and Blue Island to Mokena, with branches from Gresham to Pullman Junction, 95th St to Kensington, and Pullman Junction to Irondale.

The Cicero Central Railroad is a one-mile switching road at Cicero which serves the Koppers Chemical plant.

The Indiana Harbor Belt Railroad is a switching and terminal railroad jointly owned by Conrail Shared Assets and Canadian Pacific.

The mainline runs from Hammond, IN 39 miles around the west side of Chicago to a connection with the Metra Milwaukee District West Line at Franklin Park.

The major yard on the line is Blue Island Yard, located in the suburb of Blue Island.

The Manufacturers’ Junction Railway operates 6 miles of trackage in Cicero, Illinois.

Interchange is with Belt Railway and other roads which connect with BRC.

Steel mill railroad owned by Mittal Steel Company. The main line runs between Pullman Junction, IL and Whiting, IN with branches to South Deering, IL and East Chicago, IN.

The Chicago Terminal Railroad is no longer in operation. Their C&E Line (ex-Milwaukee Road) has been abandoned, and may be turned into a rail trail. Operations at the Centex Industrial Park in Elk Grove Village were taken over by the Chicago Junction Railway. Operations at the Bensenville Industrial Park are now handled by the Chicago, St Paul & Pacific Railroad.

Frequencies listed below may be used by the Chicago, St. Paul & Pacific.

The Burlington Junction Railway operates the Rochelle Railroad under contract with the City of Rochelle. 

Note: 160.950 may also be used at the Quincy, IL operation.

CFtW&E operates the fomer Conrail Fort Wayne Secondary (ex-PRR).  

Iowa Interstate operates the ex-Rock Island main line from a conenction with the CSX New Rock Subdivision at Bureau, IL to Council Bluffs, IA, with a branch from Henry to Peoria.

Wisconsin and Southern operates several former Milwaukee Road and C&NW lines mostly in Wisconsin; one line extends from Zenda, WI to Fox Lake, IL, with trackage rights to Chicago over Metra.

Wholly owned and operated subsidary of CP Rail. Former Milwaukee Road track from Elgin west to Iowa that had been sold off to the Iowa, Chicago & Eastern, later merged with the DM&E which in turn was bought out by CP Rail. Radio info listed with CP Rail.

The Kankakee, Beaverville & Southern Railroad operates several intersecting lines in Illinois and Indiana:

Kankakee, IL to Sheldon, IL (ex-NYC)
North Hooper, IL to Danville, IL (ex-Milwaukee Road)
Cheneyville, IL to Lafayette, IN ((ex-NKP / LE&W)

Operations on the Chicago area lines formerly run by CIRR have been taken over by BNSF (owner of the lines).

Alton & Southern is a switching road in the greater St. Louis area.  Gateway Yard 

The Bloomer Line operates the ex-IC line from Kempton to Colfax via Strawn, and a former Wabash branch from Strawn to Gibson City.

D&EI (reporting marks DREI) operates two lines acquired form CSX Transportation, and one acquired from NS:

DREI Danville Subdivision: Danville, IL to Terre Haute, IN (ex-NYC)
DREI Decatur Subdivision: Decatur, IL to Hillsdale, IN (ex-B&O)
DREI Charleston Subdivision: Metcalf to Neoga (Eastern Illinois RR, ex-Nickel Plate / Clover Leaf)

See the WIKI for additional business frequencies and information 

Decatur to Assumption (ex-IC)

The Effingham Railroad is a 1.5 mile switching road connecting to CN and CSX in Effingham.

Pekin to Springfield and Taylorville, via Havana and Petersburg (ex-Chicago & Illinois Midland Railway).

Illinois Western is a switching road which connects to CSX at Greenville and BNSF at Smithboro. (Bond County)

The Keokuk Junction Railway operates several lines of the original Toledo, Peoria & Western Railway:

33.5 miles, Warsaw, IL to LaHarpe, IL (ex-TP&W Third Subdivision)
88.1 miles, Lomax, IL to Peoria, IL via LaHarpe (ex-TP&W Second Subdivision)

The Shawnee Terminal is a 2.5 mile switching railroad in Cairo, IL which interchanges with Canadian National. The line may be out of service.

The Tazewell & Peoria is a terminal railroad (the former Peoria and Pekin Union Railway), connecting UP, NS, CN, BNSF, TP&W, Iowa Interstate and the Illinois and Midland.

TRRA is a switching and terminal railroad in the metro St. Louis area, serving local customers and connecting BNSF, CN (ex-IC), CSX, NS and UP, as well as KCS.  More info in the wiki

The TP&W operates 247 miles of the original TP&W from Mapleton, IL to Logansport, IN via Peoria. Portions of the old TP&W west of Peoria are operated by Keokuk Junction.

The Indiana Rail Road Indianapolis Subdivision operates over 155 miles of the former Illinois Central line from Newton, IL to Indianapolis, IN. The railroad's Chicago Subdivision (ex-Milwaukee Road) runs from Terre Haute, IN to Burns, IN but does not enter Illinois; INRD reaches Chicago via trackage rights on CSX.

The Vandalia Railroad operates 5.5 miles of former Illinois Central trackage and connects with CSX at Vandalia.