WASHINGTON - The center of the Republican presidential coalition is moving toward the distant edges of suburbia.

In this month's election, President Bush carried 97 of the nation's 100 fastest-growing counties, most of them "exurban" communities that are rapidly transforming farmland into subdivisions and shopping malls on the periphery of major metropolitan areas.

Together, these fast-growing communities provided Bush a punishing 1.72 million vote advantage over Democrat John Kerry, according to a Los Angeles Times analysis of election results. That was almost half the president's total margin of victory.

"These exurban counties are the new Republican areas, and they will become increasingly important to Republican candidates," said Terry Nelson, the political director for Bush's re-election campaign. "This is where a lot of our vote is."

These growing areas, filled largely with younger families fleeing urban centers in search of affordable homes, are providing the GOP a foothold in blue Democratic-leaning states and solidifying the party's control over red Republican-leaning states.

They also represent a compounding asset whose value for the Republican Party has increased with each election: Bush's edge in these 100 counties was almost four times greater than the advantage they provided Bob Dole, the Republican presidential nominee eight years ago.

In states such as Ohio, Minnesota and Virginia, Republican strength in these outer suburbs is offsetting Democratic gains over the last decade in more established - and often more affluent -inner-tier suburbs. As Democrats analyze a demoralizing defeat in this month's presidential election, one key question they face is whether they can reduce the Republican advantage on the new frontier between suburbs and countryside.

"When any party is losing a growing group of voters, that's a problem - and this is a group where support for Democrats is diminishing as the size of the group grows," said Mark Mellman, Kerry's campaign pollster.

The Los Angeles Times analyzed the 100 counties that the Census Bureau identified as the fastest growing between April 2000 and July 2003, the latest date for which figures were available. Stretched across 30 states, these counties grew cumulatively over that period by more than 16 percent, reaching a total population of 15.9 million.

These are places defined more by aspiration than accumulation, filled more with families starting out than with those that have reached their earnings peak.

They include Union County, N.C., 25 miles southeast of Charlotte, where poultry farms are being converted into new developments so quickly that nearly one-seventh of the population is employed in construction. In Douglas County, Colo., about 20 miles south of Denver, so many young families have relocated that the budget for the local Little League is estimated at $500,000 a year.

In this month's election, Bush romped across this terrain, the Times analysis showed. Of these 100 fast-growth counties, Kerry carried three: Clark County, Nev., which includes heavily unionized Las Vegas; Chatham, N.C., near Chapel Hill, where Kerry is holding a five-vote lead pending a recount; and tiny Nantucket, Mass., which made the fast list only because it increased its population of 9,520 by about one-eighth.

In almost all the other fast-growing counties, Bush not only beat Kerry, he beat him badly.

In a handful of these counties, officials are still finalizing their vote tallies. But based on virtually complete totals for the 100 counties, Bush took 70 percent or more of the vote in 40 of them, and 60 percent or more in 70 of them. In all, Bush won 63 percent of the votes cast in these 100 counties.

That broad appeal, combined with the rapid population growth, allowed Bush to generate much greater advantages from these counties than he did four years ago. In 2000, Bush won 94 of the counties, but they provided him a smaller cumulative advantage of 1.06 million votes.

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