| Capital Transit Co. | 1933 |
| Montgomery Bus Lines | 1927 |
| Inter-county Transit Corp | 1959 |
| Washington Railway and Electric Company | 1902 |
| Capital Traction Co. | 1895 |
| Washington Coach Co. | 1926 |
| Suburban Coach Co. | 1928 |
| Washington Rapid Transit Co. | 1921 |
Silver Spring Transit Company became the Suburban Transit Company which became the Inter-county Transit Corporation in 1959. Sold to DC Transit in 1960
See seperate page
| Washington and Georgetown Railroad | 1862 |
| Rock Creek Railway bought the rail line of the Chevy Chase Land Co. in 1892 | 1888 |
| Washington and Maryland Railway formed from the Baltimore and Washington Transit Co. (1894) and the Baltimore and Ocean City Railway (1906) | 1916 |
