Beginning in 1921, intrastate bus service was regulated by the Illinois Commerce Commission. Although some regulatory decisions were made by the predecessor agency Illinois Public Utilities Commission.
Illinois Commerce Commission regulation also included local public transportation. Including the companies which evolved to the CTA and Pace systems in the Chicago area. The first bus company regulated by the Illinois Commerce Commission was Chicago Motor Bus Co. in 1917, which later became Chicago Motor Coach Co. A Certificate of Convenience and Necessity was awarded for each of the Chicago Motor Coach systems on the north, south, and west sides of Chicago. Additional major decisions were made in 1928 and 1930, when there was a need for expanded public transportation on the northwest side of Chicago. In 1928, when the regular Chicago Railways streetcar system was not prepared to expand and meet the needs, Chicago Motor Coach was permitted to introduce new bus routes in the area. But in 1930, the decision was reversed, and Chicago Railways erected wires and introduced Chicago's first trolleybuses.
Information from the "Opinions and Orders" from the Illinois Commerce Commission, on the awarding of each Certificate of Convenience and Necessity to a bus operator. Information is available through the first half of 1948. Although between mid 1933 and 1936, those volumes are missing from both the Chicago Public Library and the University of Chicago Library. But the most important of those decisions are referenced in later volumes, and as many of them as possible are included here.
These lists focus mainly on interurban and intercity bus routes. And for local city transit systems, generally listed is only the first bus service either supplementing or replacing some streetcar service. These lists are organized by the Case Number, assigned by the Illinois Commerce Commission.
Case Numbers 0-9999
Case Numbers 10000-14999
Case Numbers 15000-19999
Case Numbers 20000-29999
Case Numbers 30000-39999