Since you are from Ohio, you oughtta know. However, the Wikipedia article on RFD (now RR) addresses indicates that they usually include a box number. I don’t know if this was the case back in the 30s, but it seems possible to me that Mr. Boynton’s address included a box number (11? 11x?) and some NYC secretary screwed up and put it on the last line.
Here’s an image of what appears to be a similar type of mailing – from a business to an individual.
http://www.mayoph.com/images/99C430.JPG
The postage was apparently $.01 and the letter was apparently sent around 1935.
Here’s one from 1940, and the postage was apparently $.03.
http://www.owasu.org/gallery_pics/glass02.jpg
Here’s one from 1941, and the postage was apparently $.03:
http://www.worldmeterstamps.com/mss/images/40due.jpg
You could probably find more examples with a few google searches, but it looks like the rates for this type of mailing went up some time around 1940.
So I’m gonna guess that the letter was sent in the 1930s.
If it’s any help, addressee Sidney Hale Boynton was born on 9 January 1882 in Elyria, Ohio.
In 1942 he lived with his wife Juanita in Elyria, Route 3, and worked for the National Tube Co. in nearby Lorain, Ohio. He was 5 ’ 9 " tall, had blue eyes and gray hair. He died in October 1966, residing in Santa Fe, New Mexico.
The Chronicle-Telegram, Elyria, Ohio, Oct. 3, 1966:
I’m going to figure that it was sent, especially in light of what brazil84 posted, in the later half of the 30s, which is more than enough to settle my curiosity.
Certainly the right person, as I’m in Santa Fe. Interesting.
I came by the envelope at work, where it was tucked into a book in one of ten boxes of donations. I didn’t get the chance to speak to the donor, but as I’m the type of person who likes what can generously be described as “old crap”, I was enthralled by the little things tucked amongst the books. Old envelopes, newspaper clippings, and dozens of corporately-sponsored recipe booklets from around the 1950’s, which all seem to have the singular intent of clogging your arteries as fast as humanly possible.
those are the best kinds! My wife once went to throw away a '50s reprint of a '00s Hershey’s cookbook (to my horror of course!), when I stopped her. She now uses about 8 of the recipes in that book as her “stock items” when a need for chocolate & baking occurs.