Nice shot of times gone by. I was runt and could fit in the "well" behind the rear seat in a VW Bug...
I think the last drive-in movies I saw was on a weekend pass in boot camp 1976 - Rollerball and Logan's Run.
But, there is still the functioning Skyline Drive-In.
31175 Old Hwy 58, Barstow, CA 92311
Besides that in Barstow, there is the Route 66 museum next to the Western America Railroad Museum.
685 N 1st Ave, Barstow, CA 92311
There are also some Route 66 relics/renovations to be found around town - old restaurants and motels, and a few landmark buildings, etc. Calico ghost town is 20 minutes away. You can actually have a nice (temperatures permitting) weekend there.
The Santa Fe Springs CA drive-in retains some of the drive-in signage but is now an everyday swap meet with other entertainment.
13963 Alondra Blvd, Santa Fe Springs, CA 90670
One of the series of Pacific Drive-in Theaters "near" Disneyland operated 1949-1993 until sold for residential development.
6612 Lincoln Avenue Buena Park CA 90620
http://cinematreasures.org/theaters/4005
Not to overstate the obvious, but Route 66 is becoming less of what it was, on a continuous basis. One of the iconic stone gas stations was finally bulldozed a few years back after becoming too unstable to remain propped up. Still a bunch to see and do, and you can still sleep at the Wigwam motel in Holbrook AZ. I have traveled all of it in California and Arizona a couple times. Not sure if Shaffer's fishbowl ("near" Oatman AZ) still has the two fish I saw in the very murky water.
A history of the Shaffer Spring Goldfish Bowl on Oatman Road