1903-1905 - Everett Railway & Electric Co. (Everett-Snohomish)
1905-1907 - Everett Railway Light & Water Co.
1907-1912 - Puget Sound International Railway & Power Co.
1906-1912 - Seattle-Everett Traction Co.
1912-1930 - Pacific Northwest Traction Co.
1930-1949 - North Coast Transportation Co.
Interurban lines:
Seattle-Everett (1906-1939)
Everett-Snohomish (1903-1921)
Mt. Vernon-Bellingham (1913-1931)
Mt. Vernon-Sedro Woolley (1913-1925)
Replacement bus companies:
Pacific Northwest Traction Co. (1922-1929)
North Coast Transportation Co. (1926-1949)
North Coast Greyhound Lines (1949-1950)
Northwest Greyhound Lines (after 1950)
1902-1902 - Seattle-Tacoma Interurban Railway Co.
1902-1928 - Puget Sound Electric Railway Co.
Interurban lines:
Seattle-Tacoma (1902-1928)
Tacoma-Puyallup (1908-1918)
Replacement bus companies:
North Coast Transportation Co. (1926-1949)
North Coast Greyhound Lines (1949-1950)
Northwest Greyhound Lines (after 1950)
1891-1892 - Tacoma & Steilacoom Railway Co.
1892-1899 - Tacoma Railway & Motor Co.
1899-1916 - Tacoma Railway & Power Co.
Interurban lines:
Tacoma-Steilacoom (1891-1916)
1896-1916 - Seattle Renton & Southern Railway Co.
1916-1937 - Seattle & Rainier Valley Railway Co.
1928 - buses introduced
Interurban lines:
Seattle-Renton (1896-1937)