Bryan Caplan argues that there are two reasons to argue in favor of immigration, basic fairness (how is it fair to punish someone for being born to the wrong parents?), and the net greater good (immigrants in total provide much more positive economic impact than anything they take). More than that, I would also argue that the USA needs immigrants, not just for economic growth, but to continue the uniquely American tradition of a melting-pot society. We are a country of immigrants, and it has made us dynamic and innovative and strong. I wonder if without the continuing influx of changing culture, new ideas, and the enthusiasm and optimism required to immigrate, our country may stagnate both economically and culturally.

On the topic of economic growth and immigration, Mr. Caplan says:

When driverless cars arrive, you can count on people to complain that they’re putting truck-drivers out of work. But by this logic, we’d be richer if law-makers in the 19th-century banned the tractor. The fundamental truth of economic growth: While innovation often hurts immediate competitors, it is the fountainhead of rising prosperity.Doesn’t immigration hurt workers by increasing the supply of labor? It’s complicated, because immigration also increases labor demand. After all, workers buy stuff. To grasp immigration’s full effect, keep both eyes on production. Trapping Mexican farm workers on primitive Mexican farms starves them and us. It’s far better if they move here and enrich themselves by putting better and cheaper food on our tables.

Like driverless cars, immigration can impoverish some Americans while enriching the rest.

The experience of USA with immigration speaks for itself. Why are we putting so much of our resources into keeping out exactly the people who have the most to contribute to all of us?

Edit 4/28/14: Here’s a great post from Motley Fool explaining exactly why we NEED immigration. One graph, keeping in mind the net gain for US is entirely due to immigration: