1) very early in the days of mass market publishing: Red Arrow - 1939 and Bantam - 1940.
2) not located in New York: Red Arrow - Milwaukee, Wisconsin and Bantam - Los Angeles.
3) complicated publishing histories: Red Arrow with four versions of its 12 books and Bantam with two or three versions of all but one of its 29 books.
4) both publishers used illustrated and type only covers. Bantam on eight books (plus one with illustrated only).
Bantam is usually referred to as LA Bantam to distinguish it from Bantam Books of New York which started in 1945.
One intriguing aspect to Bantam is that the books were apparently sold through vending machines. I say apparently because I'm not sure the authority for this. Some of the ads on the back cover imply the books were sold in stores. Perhaps both methods were used.
The books are 100 pages and at least two have a 10 cent price (another at 192 pages and 15 cents) which is much below the typical 25 cent price of other paperbacks at the time. The book subjects are a very mixed lot - a Shadow and a Tarzan, mysteries, collections of poems, health and self help, western, children's, humour. Here are the first eight plus images of three of them.
1 The Spanish Cape Mystery Ellery Queen
2 Little Known Facts About Well Known People Dale Carnegie
3 Your Health Questions Morris Fishbein
4 Everybody's Dream Book anon.
5 How to Make Friends Easily S. Currie
6 Jokes and Wisecracks Jerome Gregory
7 The Voice of Experience
8 Favorite Poems Henry C. Brown (ed.)
LA Bantam 2
LA Bantam 2 back cover
LA Bantam 3
LA Bantam 8