DENVER — There's a burning concern in the American West — almost an obsession — that Democrats will not touch in their convention here. Nor will Republicans in St. Paul. It is the U.S. population explosion. The West is feeling the brunt of it, as flowing lava of housing developments and big-box crudscapes claim its cherished open spaces — and increasingly scarce water supplies.

The U.S. Census Bureau now expects America's population to top 400 million by 2039, far earlier than previously forecast. The 300-million mark was hit only two years ago, so if this prediction is correct, the headcount will have soared by 100 million people in 33 short years.

America's fastest-growing region has been and will continue to be the Intermountain West. Its megalopolises — centered on Denver, Phoenix, Las Vegas and Salt Lake City — are set to add 13 million people by 2040, according to a Brookings Institution study. This would be a doubling of their population.

Hyper-growth still brings out happy talk in some circles. The Brookings report looks at the population forecasts for the urban corridor on the eastern face of the Rockies, spreading from Colorado into Wyoming, and enthuses, "Such projections point to a huge opportunity for the Front Range to improve on the current level of prosperity." There are challenges, it says, but they can be met — and you can almost hear local hearts breaking — by new roads, bigger airports, more office parks.

And where oh where are they going to find water? Every county in Colorado was declared a federal drought disaster area in 2002, when the population stood at 4.5 million. It is expected to approach 8 million by 2035.

As former Colorado Gov. Dick Lamm notes, the region is so dry that you can still see the wagon wheel trails laid down in the 1840s. "This is an area that plans to add 13 million people?" Lamm said to me. "Crazy."

Why isn't the population boom being discussed at the party conventions? Because its main driver is immigration — both the number of newcomers and their high birth rates. (The region is also trying to accommodate people relocating from other parts of the country, many of them trying to escape congested California.)

Promoters of open borders like to drag race into any discussion of immigration, so that even those who focus on numbers, not skin color, fear to speak. The Sierra Club leaders have gone into hiding on the matter. Even when you limit the subject to illegal immigration, they're under the bed.

In 2004, Lamm and two other environmentalists wanting to address population pressures ran for the Sierra Club's board. They all lost after the club's executive director, Carl Pope, announced that "they are clearly being supported by racists." (One of them, Frank Morris, had been director of the Congressional Black Caucus Foundation.)

The full story can be found at www.susps.org. SUSPS used to call itself Sierrans for U.S. Population Stabilization. Fred Elbel, a former director and Denver resident, describes himself as a liberal Democrat who left the party in frustration over its failure to confront the demographic realities of immigration.

"It's called the third rail," Elbel told me. "But immigration and urban population growth will be the defining issue for our country in this century." The parties do talk about immigration, he adds, but never its environmental implications.

For sure, the two national parties will be jabbering on about the nation's groaning infrastructure, global warming and, in deference to the West (and South), the water crisis. But you can bet that they won't go near the thing that makes all these problems worse — America's exploding population.

To find out more about Froma Harrop, and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate web page at www.creators.com.

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