Beginning in 1916, intrastate bus service was regulated by the Maryland Public Service Commission. The Annual Reports were lacking in further information regarding the early bus companies. But the February 1922 issue of the publication "Bus Transportation", lists the operators and routes at the time.
Operator Route C. O. Albright Cumberland-Ellerslie/Zembower's Store John L. Adams Cambridge-Claiborne Frank Buttion Baltimore-Chesaco Park Leonard C. Burns Washington-Brooksville-Ashton Leonard C. Burns Olney-Ellicott City V. M. Barnett Chestertown-Tolchester Baltimore Transit Co. Baltimore Lewis H. Blair Clearspring-Hagerstown H. N. Burgoon Manchester-Greenmount Charles L. Cook Lakeshore-Brooklyn (Baltimore) Wm. E. Conway Westminster-Reistertown Oden C. Coffin Westminster-Littlestown PA Denton Auto Bus Co. Denton-Ridgely/Greensboro Wm. L. Dean Cambridge-Hurlock Robt. P. Droneburg New Market-Frederick Emmitsburg Motor Co. Emmitsburg-Taneytown Emmitsburg Motor Co. Thurmont-PA State Line Roy R. Gosnell Frederick-Brunswick Roy R. Gosnell Baltimore-Frederick Stewart A. Geisbert Baltimore-Frederick W. C. Ham Baltimore-Frederick Harry G. Lescalleet Baltimore-Frederick C. L. Wood Baltimore-Frederick Gladhill & Sonder Frederick-Washington DC Frank E. Sheffield Frederick-Washington DC Willie V. Wolfe Frederick-Washington DC E. V. Hull Smithsburg-Hagerstown Walter H. Hadaway Rock Hall Ferry Pier-Rock Hall Charles Harvey Curtis Bay-Hall's Church Wm. A. Webb Leitersburg-Waynesboro PA Harry N. Hopkins Belair-Havre de Grace Lashley & Anderson Cumberland-15 Mile Creek/Cresaptown Claude J. Lewellyn Capitol Heights-Washington DC Wm. B. Loller Earleville-Middletown DE McMahon Transportation Co. Overlea-Belair Wm. Miller Lansdowne-Morrell Park J. N. Marshall St. Michaels-Easton Taylor W. McKenny Elkton-Chesapeake City Owens & Stokes Sharptown-Salisbury Pebrie & Harshman Hagerstown-Waynesboro PA Dominick Rossi Belair-Darlington/Shawsville Philip Restivo Gwynn Oak Jct.-Westminster/Sykesville W. E. Rinard Mt. Savage-Cumberland Royal Auto Service Co. Washington DC-Bradbury Heights Philip G. Schatz Laurel-Baltimore Oscar F. Smith Salisbury-Fruitland Christopher Seling Baltimore-Poplar Louis Slocum Cambridge-Claiborne/Salisbury/Hurlock Harry V. Steiger Hagerstown-Mercersburg PA Salisbury-Berlin Transit Co. Salisbury-Berlin Alfred C. Stiltz Elkton-Newark DE-Wilmington DE F. L. Simpson Libertytown-Frederick Tidewater Lines Washington DC-Brandywine/Waldorf-Rockpoint Tidewater Lines Waldorf-Leonardstown Tidewater Lines La Plata-Doncaster Tidewater Lines Washington DC-Cedar Hill Cemetery-Silver Hill Tayman Bus Line Washington DC-Lothian Taneytown Garage Co. Taneytown-Westminster Walter V. Trail Baltimore John J. Twigg Frostburg-Grantsville Ultimate Sales & Service Co. Washington DC-Edgewood Union Transfer Co. of Allegany Cumberland-Kelly Springfield Tire Plant W. Scott West North Beach-Chesapeake Beach West Shore Transit Co. Annapolis-Solomon's Island Worcester Transit Co. Snow Hill-Pocomoke City Ashby Wood Brooklyn-Morris Hill Fayette Street Motor Bus Line Baltimore