Curt, I'm glad you said '10 favorite American films' and not '10 greatest American films' because personally I don't think anything Hollywood has put out in the last 35 years should even sniff 10 greatest, especially anything with Brad Pitt(Fight Club), and I'm only 34, but I digress.  My 10 favorite, in no particular order:
1. Night of the Hunter
2. Rebecca
3. Frankenstein
4. Brute Force
5. White Heat
6. Sunrise
7. Elmer Gantry
8. Sahara
9. Shane
10. The Great Escape