A listing of public photo archives with lots of San Francisco transit photos, many of them searchable.
Market Street Railway’s own public Flickr group, with thousands of photos from the last 10-30 years of streetcars and cable cars.
The SFMTA photo archives, dating back into the 19th century and including official photos from United Railroads, Market Street Railway Company (our namesake) and the San Francisco Municipal Railway (Muni). You can search by year, by route, by neighborhood, and much more.
The Western Neighborhood Project’s opensfhistory.org has a wonderful collection of photos of San Francisco Past, including a great many with streetcars and cable cars in neighborhoods all over town. You’ll be down the rabbit hole within seconds!
The San Francisco Public Library photo collection can be accessed here, with tips on how to find what you’re looking for.