The only really good places I found with the infamous RT66 signs etc was in the Flagstaff AZ area... Alot of RT 66 shoots off of I40 along that path... California also has long sections of RT66 road way...
We all want to get our picture standing next the the RT66 sign with beautiful Arizona mountains in the back ground...
Mine are in a book somewhere and didn't make to this computer pictures folder...

Google Image
Driving from Chicago to the West Coast on RT66 is not going to happen haha... Only sections along the way will be identified as RT66... Basically RT66 got replaced by I44 out of Illinois and picking I40 in Oklahoma on West...

We better go see it before it completely goes away I reckon...
Roy Ken