Well, it's been a long time since I dealt with the US immigration. AAMOF, I don't think I've ever dealt with them. They are no longer the INS, but the USCIS, and they're in the new Department of Homeland Security. Wikipedia also has information about US immigration history. There are many links at the bottom of the article you should explore. They also have another article about the US immigration debate, complete with links to more information at the bottom.
Good luck finding information for your debate!
