[4] Construction involved lowering Stockton Street near where it passes into the tunnel from the south, evidence for which can still be seen at the building of 417 Stockton Street (Mystic Hotel), where the basement became the ground floor and the former front door is now a visibly marked window bay on the second floor.

[6] A petition was filed for a new streetcar line by Frank Stringham, representing an unnamed group of investors, with the San Francisco Board of Supervisors on January 23, 1909.

Instead, Skaller turned to the idea of public funding through a special assessment district, labeling the project as an "improvement" for existing roads.

[7] The Stockton Street Tunnel Association launched its fundraising campaign in May 1910, hoping to raise $450,000 (equivalent to $14,720,000 in 2023) to cover construction costs by creating a special assessment district to fund the improvements.

[9] Two assessment districts were set up, in North Beach and Downtown, and projected traffic was estimated to reach 50,000 to 75,000 passengers per hour during the Panama–Pacific International Exposition of 1915.

In 1984, prodded by Chinatown advocates, San Francisco added safety rails for the sidewalk, new lighting, and waterproofing, after a pedestrian was killed by an automobile.

[17] SFGATE has remarked on the tunnel's use by filmmakers, noting in particular the "crooked" topography at its southern end at Bush and Stockton streets: "Many dimensions are blurred on the cryptic intersection.