I know very little about US censorship markings from World War 2 and I am hoping someone can help me understand the one on the illustrated flight cover and where in its journey was likely applied. All I know for sure is that the cover was flown starting in Cairo, Egypt on May 25, 1942 where it received the small dark purple circular rubber stamped bilingual (Arabic/English) "POSTAL CENSOR" marking. It was then flown by Pan Am Africa by land plane down to Khartoum then across central Africa to Nigeria then along the western Africa coast to Liberia where it was loaded onto a Pan Am flying boat and flown to Brazil then northward across the Caribbean to Miami, where it was then flown by land plane to New York City. At some point along the way, perhaps Miami?, or perhaps somewhere else?, it received the larger round light purple US censor rubber stamped marking that reads "U.S. CENSORSHIP" around the top edge and then 3 outline stars at the bottom and in the middle "PASSED BY __________" with no censor's number filled in the underlined area. I would appreciate any help in identifying and understanding this particular US censorship marking. It is similar to ones I have seen on other WW 2 era covers though the others I have seen have had variations on the three stars at the bottom.
Thanks for anything you can tell me!