This image shows a very small segment of one of the many freeways that wind their way around and through the Los Angeles basin.
The description states:
Los Angeles, California
A vital link in Los Angeles’ rapid expansion. Beautiful snow-capped mountains in distance.
–Given their height and size, the mountains are most likely the San Gabriel Mountains, which form the northern border of the Los Angeles basin.
It is difficult to identify this particular highway designation, as it was undoubtedly replaced when the Interstate system was completed.
The cars visible here indicate this image dates from the 1950s.