America’s 300 millionth person will be here any day now. The Census Bureau has combined birth, death and immigration rates and expects him or her to arrive in mid-October. No one knows where or how - squalling in a birthing room in Los Angeles, maybe, or darting out of the desert east of Phoenix. That’s too bad, because whoever it is should get a bouquet and a thank-you card. It should be signed by President Bush on behalf of a grateful nation that is buzzing with a youthful energy for which the aging powers of Europe would gladly trade their pension obligations. If the newcomer is an immigrant, he or she should also get an apology from Bush for the scarcity of worker visas, and a promise to get right on that problem.

In US, growth and vitality is the same thing. The engine of assimilation hums on, with immigrants’ children trading their mother tongues for teenage upspeak with clockwork regularity.

Annoyingly brilliant young people, of whom we have lots, keep coming up with world-upending ideas like Apple, Google and YouTube. Our teeming immensity keeps us from going stale, and despite some people’s panic attacks, our population issues have mysterious ways of working themselves out. America has big problems, but it also has 300 million reasons to be hopeful.