Some Cancels On The Back Of Envelopes

Hello,

I am not an expert for postal history and envelopes with their cancels. I know about the regular cancels as well as registered cancels and receiving cancels.

But I found some interesting ones which I would like to show and ask:
- are transit cancels just as common as receiving cancels or do they add premium to a "normal" envelope with a common stamp?
- what does the "D" cancel mean?
- somebody has perhaps an example of this red New York PO box cancel so that I could compare under magnification? (it's not possible to scan better).

Of course, if one of those cancels is a very interesting one, I show the cover completely, but if all are just common, my questions would nearly be already answered.

thank you.

Transit cancels do add to the postal history of cover, but maybe not too much to the monetary value. It all depends on the type to which there are many. #1 is probably the more interesting cancel as a late mail cancel. The others are much more common as they are from big cities. I believe the D is the station, but someone else might know better.

thank you, that really helps already. Of course I read everything that others will add (for example about the D), but I guess my questions are answered.