Question On Old (1928) New Airmail Service Notices

Hello, I have 3 very old (1928) airmail 'notices' from the USPO., All in very good condition for their age. They are all around 5 3/4 inches by 3 inches:

(1) Thin paper blue ink, announces airmail has been reduced to 5 cents for the first ounce. It has plenty of info on both sides and has a postmaster signature printed on it: J.J. Kiely.

(2) On heavier stock, red and blue ink printed on one side "To the Public" announcement from same postmaster. This one has New York, N.Y. on it.

(3) Similar to above but has image of airplane and is mostly artwork. But the back of it has a hand stamped postmark: March 15, 1928. Inside the circular postmark is: CHARLES WINCHELL NEW YORK CITY P.O. Box 937 City Hall Sta.

These have to be extremely rare. Does anyone know anything about these? Are collectors interested in this sort of stuff?

They are rare and would enhance an airmail collection. But, that doesn't mean that a collector would pay a large price for them.

I would call them uncommon rather than rare. Using airmail was strongly pushed in the late 1920s with fliers and other ads, especially the new 5 cent airmail rate. Some are local products, some national. They are certainly collectible, but of modest value due to a small following.

Here is one with the dealer-pencilled price of $2:




One from Cincinnati/Indianapolis dated 1927:




And a later one for Air Parcel Post, a service started in 1948.