The US 101 Freeway is composed of a few different freeways passing through very divergent areas. In the downtown area, it is the Santa Ana Freeway, mostly constructed between 1946 and 1952. North of the Four Level Interchange, it becomes the Hollywood Freeway, constructed between 1940 and 1958. It still retains quite a few of its original bridges and railing as well. With little exception, the Hollywood Freeway hasn’t been widened, making it one of the earliest examples of an eight-lane freeway. North of the 134/170/101 Interchange in the North Hollywood area, the 101 becomes the Ventura Freeway. This freeway competes with the 10 and the 405 for the “Busiest Freeway” moniker. It is a competition that seems to never end.
US 101 also has its southern terminus in the East Los Angeles Interchange. It officially begins on the Santa Ana Freeway where it passes underneath the lanes connecting to the I-10 West. Seems confusing? It is just the way Caltrans handles the routes. I-5, its traffic having left further south, is still the official route on the Santa Ana until this point. Route 5 then “steps up” to the lanes above to continue is journey north.
Santa Ana Freeway
These overhead structures are as old as the freeways (early 1950’s). These have carried all the designations ever given. The signs themselves are much younger (60’s-90’s) :
At the 101/170/134 Interchange, US 101 transitions onto the Ventura Freeway.