I dont believe a single Yost vise is made in USA at this point. When I bought my Wilton, you could still buy a Starrett Athol vise that was built here, but, that is over now as well.
Pretty much down to the remaining Reed machinists vise on the shelf at Greenshields, Milwaukee Morgans, which Greenshields is the jobber for as well, and Wilton. Only the top end vises from those companies are made in USA.
Ive got a new, 3 1/2 Morgan USA swivel vise coming, will end up on a bench either here, or, at work, depending on what I think of it.

Best,
Ted