[10] In 1902, a parallel set of tracks were added on the west side of Queen Anne Avenue, with a second underground tunnel and independent counterweight railcar.

[3] Cable cars, as designed for hilly San Francisco, were ideal for the steep northernmost blocks of the extended line.

Due to the extreme grade of the northernmost blocks along Queen Anne (between Mercer and Comstock), electric streetcars would have to rely on a counterbalance system to supplement their motors, leaving it as one of the last cable car lines in Seattle.

[1] In May 1901, Seattle Electric advanced a plan to tunnel beneath Queen Anne Hill to replace the counterbalance, but the idea was unpopular and not pursued further.

On March 5, 1937, the Seattle Municipal Street Railway held a race between the Counterbalance and a new trolleybus, powered by a temporary overhead line; the trolleybus, laden with 92 passengers, finished climbing the hill in a minute and a half, well ahead of the streetcar, which finished in just over three minutes despite the latter being given a head start from halfway up the hill.

[12] The race was arranged by the engineering firm of John C. Beeler to support its plan to convert the streetcar system to trolleybuses, but voters rejected Proposition A on March 9, 1937, which would have issued $11.6 million in bonds to finance the conversion and settle the remaining debt from the 1919 purchase of Seattle Electric.

[13][15] Eventually, with the help of a federal loan, the city began converting its streetcar system to trolleybuses, and the first "trackless trolley" started revenue service on April 28, 1940.

[16] By that time, the operator had already dealt with grease on the tracks; the youths dispersed the 40 passengers on board by pelting them with rotten fruits and vegetables.

[16] 20 were arrested later in connection with the wild scene;[1] the operator asked the court to dismiss the charges just before the trial, scheduled for September 16, was to start.