
Washington, D.C., in 1939. "Aerial view in front of the Willard Hotel at 14th Street and Pennsylvania Avenue, showing pedestrians and rather dense traffic in autos and streetcars." View full size. 35mm nitrate negative by David Myers.
The caption identifying the location as 14th Street and Pennsylvania Avenue is incorrect. There were no junction tracks between the routes at the intersection of 14th Street and Pennsylvania Avenue NW. The actual location of that picture is two block north at 14th and G Streets. the picture was taken from the upper floors of the Western Union building that still stands on the northwest corner of that intersection.
[I think you're mistaken. The caption was written by the photographer. Below, photos of the Willard and from the Willard circa 1923, showing the intersection and streetcar tracks. - Dave]

The street car in this picture are electrically powered, drawing current from a "shoe" that runs in the slot. The San Francisco cable cars are an entirely mechanical system. The cars have a grip, which is described as being like a pair of pliers, that grabs hold of a cable that runs under the street on loop from a main power station where there are electric motors for each of the lines. The cable moves and physically pulls the cars along their routes. The advantages of this system over a conventional trolley system is that the cable cars have significantly less trouble dealing with steep hills.
Notice that the two street cars have their poles down on the roof. That is because power is being grabbed from the slot between the rails. This is somewhat like the SF cable cars, but in the case of the DC cars there is a 600v direct current cable in the slot which supplies electricity to the cars. This is fairly unique to the DC system.
There are bikes in the middle of the street. And a traffic cop, remember those?
That's so funny - what "rather dense traffic" looked like as a baby!