We begin our photo tour of Mound country with the main street of Binger ("Bing-er"), Oklahoma, down which our nameless narrator was ushered:
"My train drew in at twilight, and I felt rather lost and uneasy—cut off from wholesome and every-day things—as it puffed away to the southward without me. The station platform was filled with curious loafers, all of whom seemed eager to direct me when I asked for the man to whom I had letters of introduction. I was ushered along a commonplace main street whose ruled surface was red with the sandstone soil of the country, and finally delivered at the door of my prospective host."
As you can see, today the street is paved, but the soil under the pavement is indeed red. (Lovecraft undoubtedly learned this from an Oklahoma guidebook while researching the story.)
Given the age of some of the buildings along this "commonplace main street," it is possible that some of them were standing in 1930, and thus that our narrator would have been ushered by them by the helpful and curious loafers that assisted him.