Formed 1895, with merger of Washington & Georgetown Railroad Co., and Rock Creek Railway.
Washington & Georgetown Railroad Co. - incorporated 1859, opened 1862. Operated streetcar lines on Pennsylvania Av., 7th St., and 14th St.
Rock Creek Railway - incorporated 1888, opened 1892. Operated streetcar line on North Connecticut Av., later extended east on U St.
In 1908, Capital Traction Co. opened new streetcar lines on Florida Av., New Jersey Av., and East 8th St.
Formed 1902, acquiring Metropolitan Railroad Co. and several other street railway companies during that year.
Metropolitan Railroad Co. - incorporated 1864, opened 1865. Operated streetcar line on D St. and F St., and lines on NW 9th St., SW 4th St., and East Capitol St.
Anacostia & Potomac River Railroad Co. - incorporated 1872, opened 1876. Operated streetcar line primarily on H St., most of line abandoned 1900.
Capital Railway Co. - incorporated 1895. Operated south of Anacostia River to Congress Heights. Acquired 1900 by Anacostia & Potomac River Railroad Co.
Capitol North O Street & South Washington Railway Co. - incorporated 1875, opened 1875. Operated streetcar lines primarily on NW 4th St. and NW 11th St. Renamed in 1893 to Belt Railway Co., and acquired in 1899 by Anacostia & Potomac River Railroad Co.
Brightwood Railway Co. - incorporated 1888, acquiring Boundry & Silver Spring Railway Co., which had been incorporated 1872 and opened 1873. Operated streetcar line on Georgia Av.
Columbia Railway Co. - incorporated 1870, opened 1871. Operated streetcar line primarily on H St.
Connecticut Avenue & Park Railway - incorporated 1868, opened 1873. Operated streetcar line on Connecticut Av. Acquired 1874 by Metropolitan Railroad Co.
Georgetown & Tenallytown Railway Co. - incorporated 1888, opened 1890. Operated streetcar line on Wisconsin Av.
Union Railroad Co. - incorporated 1872, acquired shortly after by Metropolitan Railroad Co., opened in 1873. Operated streetcar line on P St.
City & Suburban Railway Co. - incorporated 1898, acquiring the following two companies in that year, as well as the Maryland & Washington Railway operating in Maryland.
Columbia & Maryland Railway - incorporated 1892, opened 1897. Operated streetcar line on Rhode Island Av.
Eckington & Soldiers Home Railway Co. - incorporated 1888, opened 1888. Operated streetcar line on NE 4th St.
In 1933, the Capital Traction Co. and the Washington Railway & Electric Co. merged, forming the Capital Transit Co. And in 1936, the Capital Transit Co. acquired the Washington Rapid Transit Co. bus operation, completing unification of the transit system.