Since the CATO Institute has gotten a temporary pass to be cited on Free Republic without being attacked for its Libertarian ideas, you may want to consider what they have to say about illegal immigration and border fences.
CATO points out that increasing the number of visas for Mexicans will reduce the illegal crossings at less cost than building a wall or arresting the illegal immigrants.
CATO clearly does not have the best interests of American citizens at heart.
What do they say about building bridges?