California State Route 66 is a segmented former portion of US Route 66 located in the Inland Empire area of Southern California. Presently California State Route 66 exists in two segments which are largely aligned on Foothill Boulevard. The first segment of California State Route 66 exists on Foothill Boulevard between California State Route 210 near San Dimas east to the eastern city limit of Pomona. The second segment California State Route 66 exists from the eastern city limit of Rialto via Foothill Boulevard and 5th Street to Interstate 215 in San Bernardino. Despite the much of California State Route 66 being relinquished it does remain signed in places such as the photo above in Upland at the intersection of Foothill Boulevard Euclid Avenue. The below map provided courtesy of cahighways.org depicts the current routing of California State Route 66.
Part 1; the history of California State Route 66
The history of California State Route 66 (CA 66) begins during the 1964 California State Highway Renumbering. The 1964 Renumbering had numerous objectives which would simplify the State Highway System. The 1964 State Highway Renumbering involved eliminating the Legislative Route Numbers, removing long highway multiplexes and eliminating highway numbers which would be duplicate to the relatively new Interstate Highways. The initial route definition of CA 66 defined in 1963 during the lead up to the 1964 State Highway Renumbering was "Route 30 near San Dimas to San Bernardino."
US Route 66 was approved to be truncated from Los Angeles to US Route 95 in Needles by the American Association of State Highway Officials (AASHO) on November 14th, 1963. US Route 66 was effectively immediately removed from the Pasadena Freeway (the Arroyo Seco Parkway) with signage being truncated to downtown Pasadena. This measure left only CA 11 as the only signed highway on the Pasadena Freeway. Despite the approval to truncate US Route 66 to US Route 95 in Needles signage remained in place to Pasadena due to Interstate 40 in the Bristol Mountains not having been yet constructed.
Despite CA 66 being present no signage can be found on CA 210 eastbound directing traffic onto Foothill Boulevard at Exit 47 in La Verne.