Well – experiment with the words and try to find some Facebook groups – that is one way. “USA wholesale buyers and sellers” etc.
Alternatively, list major cities of US and contact their chamber of commerce, it’s likely that they would give you the list of businesses for free.
Okay so Quora thinks my answer may not help you as it’s short. But I know this because I have tried looking for list of wholesalers in various countries through above mentioned process. Obviously, the list will not be entire and/or up to date but it is still a list. Something is better than nothing.