USA Road ID

Route 66 started as a federal highway which required the signs marking the route being displayed on a specific sign. The sign shape is a shield or badge which is white with a black border and lettering, An example is on the PDF file, page 3-4 https://mutcd.fhwa.dot.gov/SHSe/Guide.pdf. The other signs you mention are most likely state or county road markers that are not a part of the historic route. In many areas there may be additional signs talking about the "historic" route which are also displayed along with the official federal designator.

I could find no reference anywhere. None of them sound familiar.

It isn't what it was when I drove it in 1968. It's all hacked up now.
You might want to buy the " Route 66 Guide for Travellers " for about Us$ 22.00.
That should give you a heck of a lot of local information that may interest you.

Unless someone contradicts me Mow Route 66 is a group of lawn mower dealer along 66. There is also Moovit 66 which is an APP listing bus stops along 66. You will also find MOWROUTE66 in OKLAHOMA. Have fun.

Route 66

I just drive through Missouri on my way out to get my grandson at Ft. Riley. I saw a lot of signs like this and I couldn't figure them out. I am guessing that they are local, county, township, or maybe even state, highway marker signs. I think you have to live there to know what they mean. It's kind of like Indiana with their road signs. If you are not from there, they don't make any sense.

I missed 2 and score was 280. I really think their 2 answers were wrong, not mine.

https://www.test-guide.com/dmv-test/indiana-practice-permit-...

Scored the same. Their answers are wrong. The U turn question has no correct answer.

Traveled to Chelmsford/Waltham and neighboring cities for work once in a while, many moons back. Encountered the "Thickly Settled" road signs along the windy neighborhood roads from time to time. Had no idea what it means exactly but always brought smiles to our faces for me and my colleague companion. Fond memories.

https://tnaron.wordpress.com/2009/05/19/nowhere-but-new-engl...

I guess the bottom line is that even if you don't know what the sign means, then "ignorance of the law" still does and they can still ticket you.

To me there is nothing historic about Route 66. The first cross country road was and still is Route 30 which starts in New York and ends in San Francisco. It was built before 66 was paved.
The difference is that some people got together and had congress pass a bill declaring Route 66 as historic and Route 30 people didn't. Now there is an commercial industry around Route 66.

Route 30 hasn't been decommissioned. That's the difference.

Actually there is historical status for many segments of US 30, although I don't think it is so designated by the US Congress. US Route 30 was originally known as the Lincoln Highway. In my state there are many historical markers that mark the original route of the Lincoln Highway. Many of these (especially through cities) are no longer along the current US 30 corridor. One of the original "seedling miles" for the old Lincoln Highway is only a few miles from where I live.