We're working to get this all together, but until then, here's a preview of what's to come:

     Washington Traction & Electric Co     Georgetown & Tennallytown Railway     Washington & Great Falls Electric Railway     West Washington & Great Falls Electric Railway     Boundary & Silver Spring Railway     Washington Railway & Electric Co     Brightwood Railway     Anacostia & Potomac River Railroad     Columbia Railway     City & Suburban Railway     Maryland & Washington Railway     Eckington & Soldiers Home Railroad     Capital Railway     Belt Railway     Capitol, North O St & South Washington Railway     Union Railroad     Connecticut Ave & Park Railway     Washington, Marlboro & Annapolis Motor Line     Inter-County Transit Corp     Silver Spring Transit Co     Suburban Transit Co     DC Transit of MD     Montgomery Bus Lines     Washington Rapid Transit Co     Suburban Coach Co     Washington Coach Co     Capital Transit Co     Washington & Glen Echo Railroad     Glen Echo Railroad     Washington, Woodside, & Forest Glen Ry & Power Co     Washington & Rockville Railroad     Tennallytown & Rockville Railroad     Washington Interurban Railroad     Washington Interurban Railway     Washington, Spa Spring & Gretta Railroad     Washington, Berwyn & Laurel Electric Railway     Maryland Traction Co     Columbia & Maryland Railway     Washington, Berwyn & Laurel Railroad     Berwyn & Laurel Railroad     Washington, Virginia & Maryland Coach Co     WMA Transit Co     DC Transit     Alexandria-Washington Buses, Inc     Alexandria-Camp A.A. Humphrey Bus Line     Columbia Pike Bus Line     AB&W Transit Company     Alexandria, Barcroft & Washington Rapid Transit     Alexandria Motor Bus Line     Arlington & Fairfax Motor Transport Company     Arlington & Fairfax Railway     Mount Vernon, Alexandria, Washington Railway     Washington & Virginia Railway     Washington, Arlington & Falls Church Railway     Washington, Alexandria & Mount Vernon Railway     Capital Transit Co     Washington & Maryland Railway     Baltimore & Ocean City Railway     Baltimore & Washington Transit     Rock Creek Railway     Chevy Chase Land Co     Washington & Georgetown Railroad     Metropolitan Railroad