There are other factors. I have heard that USC recognizes that high schools in CT tend to be rigorous as compared to high schools in SC. That could help your son. Also listen to the poster above from CT, whose DD got into 9 schools with merit, and sounds like a similar GPA. Everything is not as literal as some would lead you to believe (ie, 1% acceptance with this GPA). SAT scores are good and will help.
Good luck!