Went back through another retro-California blog, this time featuring the history of both CA 177s. The present CA 177 is remote desert highway connecting I-10 to CA 62 and essentially serves as a shortcut from the Inland Empire to the southern extent of Clark County. Oddly CA 177 is the first California Highway I clinched and one of the first I collected a shield from. The first CA 177 by contrast was formerly CA 79 on Gillman Springs Road and appears to have existed (at least on State Highway maps) from the State Highway Renumbering to at least 1966.
https://www.gribblenation.org/2019/04/california-state-route-177.html
Lamb Canyon Road (CA 79 between Gilman Springs and I-10) was completed as a through route in early '63; CA 79's alignment was shifted off the north end of Gilman Springs Road and onto Lamb Canyon at the time of the '64 systemwide renumbering; the remainder was unsigned CA 177. It still had Division of Highways milepost paddles citing it as CA 177 when I started attending UC Riverside in 1967; those were essentially gone within 2 years (a few stragglers hung around a bit longer). The reroute to Beaumont was first noted as a proposed route on the original California Freeway & Expressway System statewide map issued in late 1959.