Gilmore was a California-based oil company that was bought out by Socony-Vacuum in 1940, later to become Mobil. The car on the billboard appears to be a 1939 Plymouth.

Two automaker ads and one for gasoline, all aimed at the motorists coming off the bridge. The ad for gas says "Let's go to the Fair..." a reference to the Golden Gate International Exposition, a Pacific Rim oriented World's Fair.

There seems to be a large cartoon of a car on the "Gilmore" billboard but I don't know enough San Francisco history to know what that refers to. Perhaps tterrace would know?

And I remember mucilage. It came in a slender glass bottle the size of a salt shaker and had a pale red rubber top that always seemed to have dried goo all over it. I'd rather use Spray Mount these days.

It makes me think of that SF novel by Philip K. Dick, where the axis powers won WW2. In that novel, he describes a San Francisco city which never boomed in the 50's and 60's, due to the fact that the US lost the war, and that its global economy went down.

He describes the city as having kept most of its pre-war architecture, never to have developed the modern skyline we know now.

The lower level of the Bay Bridge had tracks for street cars and two lanes for trucks: an east lane and a west. The upper level had two lanes each way for cars.
John

Just to the left of centre you can make out a Key System articulated "Bridge Unit". The overhead was provided for Interurban Electric Railway and Sacramento Northern trains running on 1200 volts - in 1939 the Key System cars ran on the third rail at 600 volts. After the IER and SN abandoned passenger service over the bridge the overhead volatge was reduced to 600 volts so the Key trains could use it if the third rail failed.