Additional bus companies, listed as existing during 1930's, are mentioned in the WPA American Guide Series of state guidebooks.
For some of the earliest bus companies, listed in early reports of the California Railroad Commission, a first year or decade of operations is listed.
Chico-Paradise-Stirling City Stages - began operations late 1920's, connected Chico with Stirling City.
Hines-Williams Service - served Oroville, Lumpkin, Enterprise.
Calaveras Transit Co. - served Stockton, Murphys, Angels Camp, San Andreas, Copperopolis, Dorrington.
Delano Bus Lines - served Delano, Greenacres Subdivision, Sierra Vista Ranch.
Kernville Stage Co. - began operations in 1920, served Kernville, Bakersfield, Democrat, Hot Springs, Bodfish.
Chas. H. Loveland - served Madera to Fish Camp.
Alturas-Fort Bidwell Stage Line - served Alturas, Eagleville.
Carmel Valley Bus Service - served Carmel to Robles Del Rio.
Joe's Taxi - served Carmel Valley.
Howell Mountain Bus Line - suburban served St. Helena, Sanitarium, Angwin.
The Auburn Line - served Auburn, McClellan Field.
Auburn-Foresthill Stage Line - began operations in 1922, no further information.
Big Basin Bus Lines - served Boulder Creek, Big Basin, Santa Cruz, Feton.
Klamath River Stages - served Yreka, Hornbrook, Happy Camp, Orleans.
Vaca Valley Lines - served Vacaville, Fairfield, Travis Air Base.
Columbia Stage Line - began operations by 1920's, served Columbia, Sonora.
Jos. R. Vierra - served Comptonville, Browns Valley, Dobbins.
Marysville-La Porte Stage Co. - began operations by 1920's, served Marysville, La Porte.
Petrolia Stage - began operations by 1920's, served Ferndale, South Fork, Mattole.
Feather River Stages - served Quincy to Purdy via Blairsden.
Quincy-La Porte Stage Line - began operations in 1922, served Quincy, La Porte.
Downieville Stage Co. - began operations by 1920's, served Downieville, Nevada City.
Nevada City-Alleghany Stage Line - served Nevada City, Forest, Alleghany.
Nevada City-Grass Valley Bus Line - served Nevada City, Grass Valley.
Nevada County Bus Line - served Grass Valley, Nevada City, Auburn, Colfax, Colusa, Marysville.
Bus companies operating over longer distances than the above suburban and interurban companies, but not listed in the Russell's Guide.
Montebello Stage Lines - intercity served Montebello, Winters, Davis, Sacramento, Napa.
River Auto Stages - began operations in 1921, existed in 1930's, served San Francisco and Sacramento and Stockton.