Main routes generally still existed in 1976.
Peoria Charter Coach Co. - operated 1941-present
Original route: Peoria-La Salle
Peoria Charter Coach Co. remains in existence
Scenic Stage Line - operated 1931-1984
Original route: Hanover-Clinton
Added route: Freeport-Savanna
(originally operated by Adams Coach Line)
Trailways member (Illinois Trailways) 1982-1983
Tri-City Transportation Co. - operated 1942-1950
Original route: Cairo-Vienna
Bus companies generally listed in the July 1942 Russell's Guide or the 1952 Mass Transportation's Directory, and their predecessor and successor companies. This list is somewhat arbitrary and provides a general overview.
Bartonville Bus Line - operated 1920-1951
Original route: Peoria-Pekin
Cumberland Coaches - operated 1939-1959
Original route: Mattoon-Olney
Illinois Highway Transportation Co. - operated 1927-1972
Original route: Peoria-Pekin
1970-1972 was Illinois Highway Lines
The availability of information from the Illinois Commerce Commission is more thorough, than the availability of similar information for most other states. Including for the issuance of each Certificate of Convenience and Necessity. For most bus companies listed above, a year is indicated for when that company began operations.