I agree, GFC. Information is difficult to come by but I did read that Martin stenciled some Made in USA Whitehalls in the 60s before the name was sold to Yanigasawa in the 70s.

The later Yanigisawa Whitehalls I've seeen look like stencils of their own models. This eBay Martin Indiana looks very much like your USA Whitehall, jondolf.

https://www.ebay.com/itm/MARTIN-INDIANA-ALTO-SAXOPHONE-89612/173168122626?hash=item28519fdb02:g:jk8AAOSwYNxaiwLU

Edit: I just read that Yani stenciled some Martin instruments as well. Very confusing! But they couldn't say "Made in USA" then, could they?

The contract to supply Whitehall was with Martin, then passed to Leblanc when they bought the Martin name from Wurlitzer.  The Whitehalls became Yanagisawas because that was what Leblanc imported for various brands they were associated with.  Wurlitzer used "The Martin" name for some Evette-Schaeffer type horns they imported in the late 1960s; some of those horns may also have ended up as "Whitehall" (not nearly as desirable as the ones made by Martin and Yanagisawa).  So "The Martin" in the 1960s and 70s referred to three different models: the real American-made Martins, the Evette-Schaeffer type cheapies that Wurlitzer substituted for the real thing, then the Yanagisawa Model Six imported by Leblanc, which was a real sleeper until Yanagisawa's reputation grew in the 1980s and 1990s.