Those are the areas I remember them in as well. I used to see some of them on family vacations even in the 70's. In the 60's we took a trip from Oregon to visit relatives in North Dakota and they kept us entertained. These days all the passengers would be too busy on their smart phones t notice. I'm so glad I got to make those trips where you had to actually be in the moment the entire time! It sparked my interest in geology, geography, and culture.
We always liked those signs, on our family Road Trips, that we took in the 50’s & 60’s.... Those and the “Slug Bug” & State License Plate, Games...
We did our family road trips in a 70s disco van, some of the best adventures a person can have! We went clear to Manitoba one year, Banff/Lake Louise another, Phoenix 5 times, most of the national parks in the 5 states, plus many adventures in our home state! I feel sorry for kids these days! We even took our sons on road trips when they were little, they still rember those!
A lot of those barn ads have not been painted over. "RedMan tobacco" for one and beechnut chewing tobacco for another. I kinda miss them on the shelves behind the cigar store indian.
Having been a military brat, long road trips back to Georgia were common place. Don't recall the Burma Shave ads, but I do remember the "See Rock City" and the"Ruby Falls" signs. Slug bug was outlawed by my father as they tended to develop into full out trench warfare between my brother and I. I also remember sleeping on the back shelf behind the back seat of my dad's Impala, or just watching the cars pass at night. That would violate so may traffic laws today that it would put you in jail for life.