In 1901, Henry Bucey initiated construction on an interurban railway between Seattle and Tacoma. The Puget Sound Traction, Light & Power, a private utility backed by the Boston-based Stone & Webster Management Company, finished the project and on September 25, 1902 celebrated the inaugural run of the Puget Sound Electric Railway. Fred Sander started work on a northern line between Seattle and Everett in 1900. After limited progress, the project was turned over to Stone & Webster in 1908 and service was initiated on April 30, 1910. Work began that same year to create an interurban link between Mount Vernon and Bellingham. In 1912, Webster & Stone created a new subsidiary, Pacific Northwest Traction Company, and commenced construction of a line between Everett and Mount Vernon. The project was never completed.

Puget Sound Traction, Light & Power retained ownership of its interurban lines, but progress on Highway 99 and the post-war explosion of private trucks and automobiles ultimately doomed the system. December 30, 1928 marked the end of the Seattle-Tacoma interurban rail service. Anticipating Seattle's removal of local streetcar tracks, the company finally abandoned the Seattle-Everett railway on February 20, 1939. Anti-trust regulators intervened again in the late 1940s, forcing Puget Sound Traction, Light & Power to sell off its remaining interurban bus services. In 1950, Seattle voters narrowly authorized City Light to acquire the private firm's remaining assets and services within the city limits, ending nearly a half-century of political and economic competition.