Demographic forecasts generally take the form of predicting more of the same.
Old people have been moving to Florida for the past several years, and old people will move there for the next few years. Immigrants have been streaming in from Mexico, and they will continue to do so. You get the idea.
Most of the time these forecasts prove right. But sometimes there are inflection points, times when some trends stop and others begin. My read of recent demographic data suggest we may be at such a point right now.
These inflection points are usually not recognized at the time. For 25 years during and after World War II, there was a vast flow of blacks from the South to the big cities of the North. People assumed it would go on and on. But it stopped, abruptly, in 1965, just after passage of federal civil rights acts and at the beginning of a period of urban ghetto riots in the North. There has been no mass movement of blacks from South to North ever since, but rather a slight net move in the other direction.
Or consider the migration of millions to sunny California that started during World War II and accelerated in the postwar decades. It came to a halt in the middle 1980s, just as Southern California's President Ronald Reagan was opening the 1984 Los Angeles Olympics.
Since 1990, Americans have been moving out of California to other states in large numbers. The Golden State's population growth in the last two decades has reached the national average only because of Latin and Asian immigration.
That immigration, to California and elsewhere, is one of the two big demographic trends that has reshaped the country over the last 40 years. The other is the movement of vast numbers of people from high-tax states in the Northeast and industrial Midwest to lower-tax and more economically vibrant states elsewhere.
Both these movements have halted, at least temporarily. American mobility is near an all-time low. As in the Depression of the 1930s, people tend to stay put in hard times. You don't want to sell your house if you're underwater on your mortgage.
And immigration has plunged. The Pew Hispanic Center estimates that from 2005 to 2010, more people have moved from the United States to Mexico than the other way around. I suspect that reverse migration is still going on.
The question is whether those trends will resume when -- if? -- good times return.
My prediction is that we won't ever again see the heavy Latin immigration we saw between 1983 and 2007, which averaged 300,000 legal immigrants and perhaps as many illegals annually.
Mexican and other Latin birthrates fell more than two decades ago. And Mexico, source of 60 percent of Latin immigrants, is now a majority-middle-class country.
Asian immigration may continue, primarily from China and India, especially if we have the good sense to change our laws to let in more high-skill immigrants.
But the next big immigration source, I think, will be sub-Saharan Africa. We may end up with prominent politicians who actually were born in Kenya.
Continued domestic out-migration from high-tax states? Certainly from California, where Gov. Jerry Brown wants to raise taxes even higher. With foreign immigration down, California is likely to grow more slowly than the nation, for the first time in history, and could even start losing population.
Fortunately, governors of some other high-tax states are itching to cut taxes. The shale oil and natural gas boom has job-seekers streaming to hitherto unlikely spots like North Dakota and northeast Ohio. Great Plains cities like Omaha and Des Moines are looking pretty healthy, too.
It's not clear whether Atlanta and its smaller kin -- Charlotte, Raleigh, Nashville, Jacksonville -- will resume their robust growth. They've suffered high unemployment lately.
But Texas has been doing very well. If you draw a triangle whose points are Houston, Dallas and San Antonio, enclosing Austin, you've just drawn a map of the economic and jobs engine of North America.
Texas prospers not just because of oil and gas, but thanks to a diversified and sophisticated economy. It has attracted large numbers of both immigrants and domestic migrants for a quarter century. One in 12 Americans lives there.
America is getting to look a lot more like Texas, and that's one trend that I hope continues.