SS San Mateo was a steamship ferry operating on the west coast of the United States.

Launched in 1922, she served until 1940 in San Francisco Bay, operated by the Southern Pacific Golden Gate Ferries.

At the time of her retirement she was the last operating vehicular steam ferry in the United States.

[2] After attempts to restore her for display in a Seattle waterfront park, she was acquired by a Canadian businessman and towed in 1992 to the Fraser River in British Columbia.

[4] There she was partially scrapped; portions of her hulk are still visible in the river, and readily apparent on satellite photos, as of 2021.