Most dry summer months, somewhere in the country, a wildfire flares into a fearsome sight that fills the sky with harrowing flames and forbidding columns of smoke. During the rest of the year, state and local governments would do well to keep that frightening specter in mind when they determine where many American communities will be growing.

In too many places, people have been moving into the edges of fire-prone forests and dry grasslands, establishing a new American frontier where settlement mixes with wild landscapes. And they're counting on governments to protect them when flames break out and come roaring in their direction.

As one consequence, the U.S. government's costs to fight wildfires have soared to $2 billion per year. Roughly half of last year's wildland fires burned across national forests and on other federally owned lands. Meanwhile, state forestry agencies and rural fire departments also have been bearing a mounting share of controlling blazes that race onto state lands and private property. Last year, California's firefighting costs climbed close to $200 million, twice the amount state officials had budgeted.

With its expansive national forests and desert grasslands, the West has been particularly vulnerable to calamitous wildfires. But this spring, after months of drought, nearly 29,000 fires broke out in the South, burning more than 1.1 million acres. Several fires merged in southeastern Georgia and northern Florida, burning 600,000 acres and scorching through the Okefenokee Swamp. Moreover, during the past century, forests in the Northeast have reclaimed abandoned farms with dense tree stands.

Wildfires are clearly a national problem as millions of Americans move to sprawling exurban towns or second-home resorts that sit on the combustible fringe of forests and within hailing distance of the fastest growing metropolitan areas. During the 1990s, more than 10 million new homes were built within 15.5 miles of a national park, forest or wilderness area. In the Lower 48 states, 60 percent of all new housing units were located in what's called the wildland-urban interface. The WUI now covers 9 percent of the land and holds more than a third of the nation's population. The trend will accelerate as jobs move to suburban offices and industrial parks, baby boomers retire to rural towns and urban professionals buy bucolic weekend retreats just a day's drive from major cities. Once the buffer between civilization and wilderness, much of the country's woods, foothills and swamps have begun filling with homes that could be in the path of wildfires.

The presence of these homes makes it more difficult and costly for the government officials who are responsible for bringing wildfires under control. Last year, a U.S. Forest Service audit concluded that the federal agency has been spending up to $1 billion a year -- as much as 95 percent of the expense of fighting some big fires -- to protect homes and other structures. That's coming out of taxpayers' pockets, but homebuilders, Realtors, bankers and insurance companies haven't taken that into account as they play a role in developing subdivisions that encroach on fire-prone landscapes.

Nor, so far, have most local government land-use planning efforts. But federal and state officials are thinking about forcing counties to pick up firefighting costs unless they start regulating WUI development. Utah and Oregon have already imposed land-use planning requirements, and the Montana legislature looked at it -- although it balked this year at withholding state fire-suppression funds from counties that don't manage growth in risky terrain.

U.S. Forest Service officials are also talking up that idea, but in the words of Jim R. Wattenburger, a supervisor in Mendocino County, California, "If you start cramming building codes down our throats, you're going to make the Sagebrush Rebellion look tame." And yet, Wattenburger is a retired California state firefighter himself, and he knows that wildfires will inevitably race through the interface. After defending one Malibu mansion for the third time, he told the owner, "If you rebuild here again, I'm not coming back."

For half a century, the Smokey the Bear advertising campaign has told the public to help prevent forest fires -- and count on firefighters to do whatever it takes to stomp out blazes before they threaten lives and property. Ecologists now see fire as an elemental force that cleanses and refurbishes the natural environment. It will be a tough sell, but local officials and state fire managers need to let borderland residents know they'll not only have to live with that danger but help create it when they move into wildland neighborhoods.