Immigration - Is there an answer?

Immigration has been hotbed issue my entire life, but it seems to be taking on a renewed urgency. Is this a result of 9/11? Have we become so fearful of everyone that the pendulum is trying to swing back towards isolationism? And what is the answer?

I've heard some ideas recently on this issue that bring fear to my heart. One is requiring the police to question anyone who looks like they don't belong and if they cannot present the appropriate documentation then they're arrested. We are melting pot; how do you tell if somebody doesn't belong? How is this different from racial profiling? And as added bonus, if the police don't, they can be sued.

Another is sending our military troops to patrol our boarders.

Is this freedom?
Are we to become prisoners in our own country?
Is this what is going to bring down this great experiment in democracy?
Is there an answer?