Disagreement between Obama and Clinton. Obama said, to applause, that the inner-city unemployment of blacks isn't so clearly related to the influx of immigration as is sometimes suggested -- that it's a case of "scapegoating" immigrants.

Hillary -- trying to bring home the "Obama may sound good, but I know the details" meme -- talked about meatpacking plants and the need to recognize that immigrants do take the jobs of low-income Americans. Who's right?

This 2006 Pew study found that "rapid increases in the foreign-born population at the state level are not associated with negative effects on the employment of native-born workers." It's a widely-cited finding, like in this Bear Stearns immigration study. Make of that what you will, I'll have more in a bit.

Update: Reader JB points to the work of Berkeley's David Card, who studies the economic impact of immigration. Upshot: "evidence that immigrants have harmed the opportunities of less educated natives is scant."

--  Eve Fairbanks