Hanson: It's mastery of the language. It's acceptance of American values, and that can be everything from religious tolerance to American treatment of women to family planning to attitudes for government. …

But because we have so many people coming in and coming in under illegal auspices that we're creating almost a permanent transitory group of a million or two people who are in this process of assimilation, but not assimilation in the 19th century sense. I'm talking about a 30 or 40 or 50-year process.