I salute pguillem for doing that list which I was going to do but just did not find the time.
On the back of the copy of the bus photo I printed off my PC I have almost covered the page with incorrect guesses.
From my side, the bus is a very close replica of the Union Pacific M1000 (or M10000 depending on the reference source) engine made in the 1934-1935 time period. From what I can find, most of them were named after cities on the West Coast of the US.
The logo we see on this bus is very similar to the style of logo used on the engine for "The City of Portland" train, Portland being in Oregon. As such, I have concentrated my search to the State of Oregon. pguillem feels it comes from Illinois and he may well be more correct than I am.
According to Otto Puzzle, the bus was made "several years later than the engine",
quotation marks are mine, which would make it closer to what?? 1938-1940 maybe?
What is really baffling is that using several dozen search parameters on Google (and I do not use SBI of course) I have not found either this photo or any other photo of a similar bus. Given that I have found hundreds and hundreds of "Art Deco busses", "Streamlined busses" and I am tired of looking at Gilmore trucks, GMC Parade of Progress trucks and busses, Labatte brewery trucks etc. etc. I find it hard to believe such a unique bus was not discovered by some other enthusiast forum and commented on.
So for this post, may I ask if the venue of the truck Portland, Oregon?