Is my use of "that that" in this sentence gramaticaly correct
Grammatically it is correct. The first 'that' would be a conjunction; something like 'I thought that' or 'I feel that'.
The second 'that' would be a pronoun, such as 'that wasn't a thing' or 'that was no longer acceptable'.
Structured together would be:
I thought that that wasn't a thing anymore
I thought that that was no longer acceptable.
If it bothers you, you can usually remove one of the "that's", leaving you with: "because I thought that wasn't a thing in the U.S.A anymore".
Hope this helps!