You may check the French Universities Program at Embassy of France in USA (links & advices in French or in English) & International "Alliances Françaises" Organisation addresses... Look at Google Directories/Regional/France/Education.
Many American Universities have a connection with the Sorbonne. You can be sure of that. Many thesis were written by American natives & many books & reports were translated from English to French by Sorbonne teachers, students & lecturers.
But the American University of Paris is the best place for you. And you CAN apply both: American University of Paris & Sorbonne. They know each other perfectly. QED.
I would not go to Nanterre if I were you. It's not the safest place or the safest area. We used to go through Naterre by train to get to our home in the suburbs. It looked pretty dismal.
You're better off going to the Sorbonne. Or you could transfer to the American University of Paris.
thanks for the reply. I'll consider you warning and look in to other possibilities. Is there a lot of crime in the area of Nanterre? In which "arondisement" is it?
Nanterre is not in Paris, it is in the suburbs. Many of the French suburbs are not the safest areas (it's the opposite of the US, in which the ghettos and crime are in the cities not the suburbs).
Most of the Paris suburbs to the West are fine. This is where many American and British expats live. I think the northern suburbs are the worst, but I know Nanterre is not that great, at least it wasn't when I was there.