Writing about The Alamo last week, I quoted historian Paul Johnson on America's conflict with Mexico in the 1830s and 1840s:

"It made moral as well as economic and political sense for the civilized United States to wrest as much territory as possible from the hands of Mexico's greedy and irresponsible rulers."

Johnson goes on:

"California was an even greater prize than Texas… Considering the benevolence of its climate, the fertility of its soil, and its vast range of obvious natural resources, it is astonishing that the Spanish, then the Mexicans, did so little to make use of them."

Harvard student Richard Henry Dana sailed from Boston to California in the mid-1830s. In his famous memoir Two Years before the Mast, he recounted with astonishment that the San Francisco Bay, perhaps the finest location for human habitation in the entire world (and, as a native Los Angeleno, that's not easy for me to admit) was almost devoid of settlement. He hinted broadly to his readers that Americans could make better use of such a prize.

The American takeover of California resembled an operetta version of the more dramatic events in Texas. Political loyalties among Spanish-speakers in California were splintered among representatives of the relatively new Mexican government; those whose hearts still belonged to Spain; native-born Californios leaning toward self-rule; and those Californios (led by the impressive Gen. Mariano Vallejo) who hoped for annexation by the U.S.

The most dynamic element, however, were the American immigrants—typically New Englanders who had jumped ship and married into landed Californio families.

In 1844, California revolted against Mexican rule. In 1846, at President James K. Polk's prodding, it declared first its independence, then its allegiance to the U.S.

In 1848, gold was discovered. Hundreds of thousands of fortune-seekers rushed to Northern California. But Southern California remained a sleepy, backward cattle-raising region until the Southern Pacific railroad arrived in 1887, launching the region into the modern era with its first real estate boom. (The third main region of California is the Central Valley, where agricultural elites always wanted cheap labor.)

Subtle but important social differences emerged between Southern and Northern California. Which was the better mode was arguable—until recently.

Now, however, it has become clear that Northern California's traditional elitism has helped it withstand the onslaught of illegal immigration better than Southern California's traditional populist libertarianism.

Personally, I always preferred the greater openness of Southern California society. But that kind of freedom comes at the expense of quality of life when it's abused by millions of foreign lawbreakers.

To use David Hackett Fischer's system for categorizing the four kinds of British immigrants, Northern Californian was largely founded by New Englanders of Puritan descent. Southern California was largely populated by Middle Westerners, whose social roots typically stretch back to colonial Pennsylvania and to the South. By the 1950s, it was the paradise of the common man.

Northern California went through the typical political evolution of post-Puritans: into Lincolnian Republicans, then reformist Progressives, then modern lifestyle liberals intent, paradoxically, on preserving old-fashioned amenities like open space, traditional architecture, higher culture, and wildlife.

In contrast, Southern California was much more conservative, as the popularity of Richard Nixon and Ronald Reagan testify. But in the 1990s, much of the GOP base began to be driven into the Great Basin by illegal immigration-driven population growth. Southern California's Republican remnant, in its gated communities, is coming around to the Northern liberal point of view.

Northern California forestalled much of the dreariness of Southern California's Hispanic areas by being a high-cost economy. Ferociously powerful unions kept wages high. Stringent aesthetic restrictions and large amounts of land devoted to parks kept housing costs high. Northern Californians spearheaded the environmentalist movement—which had the unspoken but not-unintended consequence of driving up property values even further.

Southern California, in contrast, was not heavily unionized or environmentalized. It encouraged developers to put up huge tracts of homes.

Conservatives have had a hard time grasping that homeowners often use environmental laws to thwart new developments and enhance the value of their own property. Conservatives like to think of themselves as preserving property rights from meddling environmentalists. But the fact is that property owners themselves are often among those most intent on meddling.

In the ranchlands east of Oakland, for example, housing restrictions mean that most developments are dense housing pods surrounded by vast expanses populated only by cows. In the south of the state, it would all be tract housing.

The Monterey Peninsula exemplifies Northern elitism, private enterprise-style. The exquisite oceanfront Del Monte Forest is accessible only via the 17 Mile Drive, which costs an $8.25 toll to traverse, or 49 cents per mile. It's worth it, though, because much of the natural beauty has either been preserved untouched, or enhanced with the finest set of golf courses in America: Pebble Beach, the famous public course with a $395 greens fee; Cypress Point, the ultra-private "Sistine Chapel of Golf;" Spyglass Hill, Robert Trent Jones' Sr.'s best course; and four others.

Tellingly, Northern California has preserved most of its best golf courses from the Golden Age of golf architecture (1911-1933). But Southern California has lost many such courses, like George C. Thomas' Fox Hills in West Los Angeles, to housing during the post-War boom.

As a native Los Angeleno, Northern Californian snobbishness has always gotten on my nerves. Nonetheless, the payoff has become undeniable. Rather than being inundated with unskilled immigrants from one country, Northern California mainly attracts skilled immigrants from a wide diversity of countries.

The lesson for the GOP is sobering. If it won't fight to enforce immigration laws on the national level, citizens will try to parry the effects at the local level.

And the socially acceptable way to keep out swarms of poor immigrants is the Northern Californian liberal way: environmentalism, unionism, historical preservationism, NIMBYism—indeed, the whole panoply of Democratic Party policies at the state and local level.

It makes no sense for Republicans to drive conservative-minded affluent people, desperate to keep their suburb from turning into North Orange Country, into the arms of the Democratic Party.

But that's exactly what George Bush's GOP is doing.

[Steve Sailer [email him] is founder of the Human Biodiversity Institute and movie critic for The American Conservative. His website www.iSteve.blogspot.com features his daily blog.]