This picture could be just about anywhere, in 1930 a new three lane highway was constructed through an area that didn't even have a horse trail and shortened a long route significantly.
The three lane highway quickly showed how dangerous the concept was and within a few years was converted to 4-lane. The odds of this being a different highway is slim.
Over the years it has be rebuilt and realigned and is now I-5 through Santa Clarita, this is most likely a portion that was bypassed in the early 60s as freeways were being built, there are not many sections that match this curve and hill orientation.
The trucks climbing the hill in the background are on the current NB I-5