Paul Krugman has a column on immigration which, like most of what he writes, is plainly excellent. So much of recent "debate" on this topic has consisted of stereotypes being thrown around. Krugman provides some clear fact-based thinking; here is an edited excerpt:

I'm instinctively, emotionally pro-immigration. But a review of serious, nonpartisan research reveals some uncomfortable facts about the economics of modern immigration, and immigration from Mexico in particular.

First, the net benefits to the U.S. economy from immigration... are small. Realistic estimates suggest that immigration since 1980 has raised the total income of native-born Americans by no more than a fraction of 1 percent.

Second, while immigration may have raised overall income slightly, many of the worst-off native-born Americans are hurt by immigration -- especially immigration from Mexico. Because Mexican immigrants have much less education than the average U.S. worker, they increase the supply of less-skilled labor, driving down the wages of the worst-paid Americans. The most authoritative recent study of this effect... estimates that U.S. high school dropouts would earn as much as 8 percent more if it weren't for Mexican immigration.

That's why it's intellectually dishonest to say, as President Bush does, that immigrants do ''jobs that Americans will not do.'' The willingness of Americans to do a job depends on how much that job pays -- and the reason some jobs pay too little to attract native-born Americans is competition from poorly paid immigrants...

Basic decency requires that we provide immigrants, once they're here, with essential health care, education for their children, and more.... Unfortunately, low-skill immigrants don't pay enough taxes to cover the cost of the benefits they receive.

Realistically, we'll need to reduce the inflow of low-skill immigrants. Mainly that means better controls on illegal immigration. But the harsh anti-immigration legislation passed by the House, which has led to huge protests -- legislation that would, among other things, make it a criminal act to provide an illegal immigrant with medical care -- is simply immoral.

Meanwhile, Mr. Bush's plan for a ''guest worker'' program is clearly designed by and for corporate interests, who'd love to have a low-wage work force that couldn't vote. Not only is it deeply un-American; it does nothing to reduce the adverse effect of immigration on wages....

What about a guest-worker program that includes a clearer route to citizenship? I'd still be careful. Whatever the bill's intentions, it could all too easily end up having the same effect as the Bush plan in practice -- that is, it could create a permanent underclass of disenfranchised workers....

But I'd rather see Congress fail to agree on anything this year than have it rush into ill-considered legislation that betrays our moral and democratic principles.

First, I wonder if the estimates Krugman cites on the contribution of immigrants to the American economy do not underestimate the impact of immigrants to the high tech boom (personal obervations suggest that a minority of the people who work in technology companies are American).

Secondly, what about the effect on crime? Hispanics are incarcerated at a rate about twice the overall average (though there is some evidence that recent immigrants are less likely to be incarcerated).

Finally, it seems that all the proposals currently being discussed on immigration are bad. The only one that seems to make actual sense is building more walls and increasing policing on the US-Mexican border.