The USSB was effectively abolished on 02/03/1934 by executive order 6166 dated 10/06/1933 and this board was superceded by 6 other boards (various titles) and today is Maritime Administration of D of T. Try A web search.
Mark H. Goldberg has written "The Hog Islanders", "The Shipping Board's Agency Ships" and "The Stately President Liners (part 1-The 502s--650 or so pages. Part 2 on the 535s is to follow.)" for the American Merchant Marine Museum.
One piece of trivia which can be verified on the APL site.
The ships of the 502 and 535 classes were named in accordance with their length.
For some strange reason, which would make sense only to a government beaurocrat, the 502s were named for their length between perpendiculars, but the 535s for their length overall.
The two classes were did not have a 33' difference in length as most thought, but a difference of only 12'-16', depending on whether they were measured overall or between perpendiculars.
Also, many of the various lines that operated these ships used displacement tonnage, rather than gross tonnage, in their advertising, giving the impression that these liners were much larger than they really were.
Many thanks to you all for the info, it will give me a couple of angles to go on.
It gets a bit frustrating at times when you have a picture of a ship that "disapears" at some stage and it takes time to find a clue of what happen to them.
Thanks to this site i have already solved a couple of problems
I thought I'd add the poster--the fiercest damned eagle I've ever seen.
I've always been interested in these ships and I do have Mark Goldbergs's books--if there is information on a particular ship or incident, there's a slight chance I may be able to help.