Many of the illustrations for these envlopes are First Flights. The envelopes were made for Air Mail going across the Pacific and the Atlantic Oceans and were used for First Flights in that direction and in some instances First Day Covers.
- This is a FDC of the 20 cent stamp. I do not know if this envelope was used for everyday air mail across the Pacific, but it could be used for such as it states, "Trans-Pacific Air Mail", across the bottom. There is nothing stating that it is a FDC - February 15, 1937.
- "Via Trans-Pacific Air Mail, Honolulu, Hawaii" - August 26, 1938 (?).
- This envelope was used for a first flight and reads, "Trans-Atlantic Air Mail". Nothing printed on the envelope indicates this was made for only first flights - June 28, 1939.
The following two designs have always been associated with the Trans-Pacific or Atlantic flights in my mind, especially the Pacific. While there is no text indicating such on either of them, over the years I have seen them used for many such covers.