Through California Route66 followed the historic "National Old Trail Rd" (NOT) - this is roughly the (RED) alignment.
In the 1930s there were some realignments which were established with paving efforts. The most remarkable is the Bypass of Goffs Rd between Needles and Essex (BROWN - partially not mapped). This Bypass vanished underneath I-40 except of a short section between Mountain Springs exit and Essex. Further west US66 routing was simplified on it's way crossing the Mojave Desert (BROWN).
At Cajon Pass north of San Bernardino old US66 was replaced by I-15 in the early 1950s (BLUE - GREEN markers).
Until 1936 the western Terminus of US66 was located Los Angeles downtown south of Civic Center. The Pasadena / LA urban area saw many realignments due to local roadbuilding efforts during the 1930s (BROWN) and 1940s (GREEN). Eventually in 1936 Route66 was extended to Olympic Bvd, Santa Monica (BROWN). Sic..... Ocean Bvd has never been the endpoint of The Mother Road!
The "endpoint section" eastbound to Pasadena Post Office was decomissioned in 1964, the CA66 / NOT alignment was US66 until 1972/1974. Please refer to the atlas slides for further information.
In 1975 there was no US66 anymore on it's former eastbound way for the Arizona stateline.
You can take a virtual travel through California using the following CA atlas links :
|Topock to Santa Monica|