Additional bus companies, listed as existing during 1930's, are mentioned in the WPA American Guide Series of state guidebooks.
Additional information is from the "Opinions and Orders" from the Illinois Commerce Commission.
Central West Motor Stages - began operations in 1942, connecting Chicago with the Great Lakes Naval Training Station.
Chicago Ridge Transit System - as of 1952, operated 2 buses in Worth and Chicago Ridge and southwest suburbs, with route on 111th St. west of Pulaski. Probably ceased operations in 1960's.
City Transportation System - operated city service within Zion from 1946 into 1950's.
Fox Valley Coach Lines - introduced route in 1923 from Elgin to Dundee, Crystal Lake, and Woodstock, extended to Harvard in 1927. Route added in 1947 from Crystal Lake to Marengo and Rockford.
Eagle Bus Lines - began operations in 1947, connecting Chicago with various race tracks.
Franklin Park Bus Co. - began operations in 1927, operating via Grand Ave. from Harlem Ave. to Franklin Park.
Highland Park Coach Lines - operated between Highland Park and Deerfield. Controlled by Leyden Motor Coach Co.
Illiana Motor Bus Co. - in 1925 and 1926 operated two bus routes, connecting Calumet City with the Ford Motor Co. plant in Hegewisch.
Merkle Service Co. - began operations in 1927, with route from 87th St. and Ashland Ave. to Maria Cemetery near 91st St.
Ordnance Plant Bus Service - began operations in 1942, assuming route introduced previous year by Joliet City Lines, connecting Joliet with Ordnance Plant to the south.
Round Lake Transit System - as of 1952, operated 5 buses in Round Lake.
Safety Transportation Co. - as of 1952, operated between Chicago and Evanston, Glenview, Algonquin, Downers Grove. Also operated city service in Downers Grove.
Station to Lake Bus Line - began operations in 1927, providing local service in Crystal Lake.
W.A.F. Transportation Co. - began operations in 1946 with route from Woodstock through McHenry to Crystal Lake, introduced additional route in 1947 from McHenry to Crystal Lake via Wauconda. Ceased operations in 1950.
Willey Coach Lines - from 1937 to 1939 operated route from Wheaton to West Chicago.