The highway signs are dated, because they came straight out of a series of dated sign manuals. The state highway shields are also dated with a fair amount of confidence thanks to an exhaustive and impressive site:
http://shields.aaroads.com/For the rest of the signs/logos/ads, I've done my best, but just don't know for sure. Some have dates, most don't. Feel free to supply dates and I'll add them to the site.
Also, I have most of the oil company logos available as vectors, which means they can be reproduced at any size. Just PM me if you need one.