US : 1928 : July 31-St Last Day Of Old Airmail Rate :

That's a nice one. Even without the cachet, the fact that the UR corner of the envelope itself indicated the old/new US Air Mail rates for 1928 is interesting in itself.

While it doesn't show your envelope, I came across this web page illustrating a number of early US Air Mail envelope styles used through the years (and even a page on airmail etiquettes, too) which you might find interesting as it pretty closely fits this theme:

http://friends.peoria.lib.il.us/com...velopes.html

Thanks wt1,
quite frankly, I didn't know quite what I had there.

Check out Page 21 20 of this presentation for the cover (with cachet) as you have shown cancelled on the first day of usage of the new postal rate:

http://www.sandiegophilateliclibrar...sue-1928.pdf

Page 20 actually :)

Thanks again,
and I note the verbiage..."rate" cachet.

Nice little *.pdf,
not sure how you make sense of all the flight history of the US.

BTW: Cover designed by Ben Dahlke, Buffalo. NY

It's a philatelic speciality all in itself. I especially find this link interesting on many of the philatelic covers (and photographs of period planes) that were used through the early years of US Air Mail service:

http://www.aerodacious.com/

To quote a long-time member, "In 20 years SCF will be an amazing database. (if not already)"

https://goscf.com/t/17358#17358

Arrgh!
apologies Tomisek
I didn't search SCF.

I think I must have been tired at the time.....

I knew you had a good excuse reason...