While doing some research on my grandfather's military history, I managed to find a couple of US Army transport service passenger lists on Fold3. The documents present a couple of questions for me.
First, on one list dated 1924, his "Organization or Department" is shown as "A.C.", and on the other list dated 1925, it is shown as "A.S." From another document, I found that "A.S." was the abbreviation for "Air Service." There was no listing for "A.C.", but there was one for "A.S.C.", which meant "Air Service Corps." Can I safely say that all of the terms, "Army Air Corps", "Air Service" and "Air Service Corps" refer to the same organization?
Second question, the 1924 passenger list had printed at the bottom of the page the reference "Seventh Casual Company US." Can anyone elaborate on this for me? For what it's worth, my grandfather shipped in and out of San Francisco, CA., if that has any bearing on which unit he was with.