A hundred years ago, people roamed freely throughout the Americas and nobody cared. The difference now is taxpayer-provided social welfare programs.
Mexicans are our neighbors - not our enemies. We should have a robust and sensible guest-worker program, which allows them to work legally without any benefits of the welfare state.
Any man who loves liberty cannot embrace the notion of making our borders like an armed fortress. It's a stupid idea that requires oppressive government action.
I can understand and respect your demand for adherence to the rule of law. I'd just like to find a solution that allows for the maximum freedom of movement possible, without any vote-buying by politicians (which is all either party really cares about).