The Rebel yell that pierced the ears of NASCAR throughout the first half-century of the sport slowly is being silenced.

The top tier of stock-car racing has had an overwhelming Southern flavor ever since the days following World War II. The roots of the sport grew deeply into such rural towns as Rockingham, N.C., and Martinsville, Va.

But flush with cash, a billion-dollar national-television package and unprecedented popularity, NASCAR is starting to strain at its roots and stretch its limbs north and westward. Toward major urban markets with their coffers of advertising dollars. Toward glistening new tracks with sold out grandstands.

And toward a future of uncertainty for a number of older tracks that supported NASCAR back when it was the Hee-Haw of professional sports.

The first pebble fell six years ago, when the two races that took place at cozy North Wilkesboro (N.C.) Speedway were snatched away and given to tracks in Texas and New Hampshire. Now it appears an avalanche of change is on the way.

It already has been announced that North Carolina Speedway in Rockingham, which has held two NASCAR events a year since 1966, is losing one of its dates next season in order to give six-year-old California Speedway near Los Angeles a second date.

The new L.A. race will be held on Labor Day weekend, which has been the date of the Southern 500 at Darlington, S.C., since 1950. That race has been bumped to early November.

NASCAR officials seemingly are determined not to increase the schedule beyond the current 36 races a year. So the only way for the sport to move more heavily into markets outside the South is to take away races from other tracks.

"Our sponsors are national sponsors," said Joe Gibbs, who owns the cars driven by defending series champion Tony Stewart and 2000 champ Bobby Labonte. "We need to be in those big markets. TV wants it. And TV is a big deal."

Even with the sport's expansion in recent years, the majority of the NASCAR schedule still is held in the South. Of the 23 venues that hold races on the circuit, only six are west of the Mississippi River, and currently they each have only one event a season.

Strictly from a financial standpoint, the move makes obvious sense. Rockingham has only 60,113 seats, yet has been unable to sell out a race since expanding to that capacity four years ago. California Speedway, meanwhile, easily fills its 92,109-seat facility to capacity.

The racing business boomed originally in the Southeast partly because it was the only professional sport in the region at that time.

"There wasn't anything else in the area at the time that could compare to stock-car racing. There were no other major-league sports," said Kyle Petty, son of legendary NASCAR driver Richard Petty. "So people became race fans."

Conversely, the absence of NASCAR outside the South helped prevent the sport from becoming popular in those areas of the country until recently.

"I never was that interested in NASCAR until I got older and was around it, and that's because they don't have a lot of races out there," said California native Jimmie Johnson, who finished fifth in the Winston Cup standings last year as a rookie.

"There are a lot of race fans out there who are craving this. We need more West Coast dates. There is a huge fan base out there that is wanting it."

They are not alone. After only two years of existence (and two sold-out races), Kansas Speedway officials already are petitioning NASCAR for a second date.

Texas Motor Speedway officials have been clamoring for a second date for years. Las Vegas and Miami both would love to have a second race. In addition, NASCAR officials want to move into more untapped markets, such as Denver. There even are long-term aspirations of holding a race at a proposed new track near New York City.

"I've always been a big supporter of seeing the sport grow and go to the next level," four-time series champion Jeff Gordon said. "There are a couple of tracks in the Southeast that it would be beneficial if (one of the race dates) went to a venue in another part of the country in a bigger market."

One potential problem with such changes is the additional time and expense that would be required to travel to so many different parts of the country. Nearly every race team is located in the Charlotte area. The farther the teams have to travel to make it to the tracks, the more it is going to cost to compete in an already-expensive sport.

"We don't need to spend more," Labonte said. "It costs less to go to Rockingham than it does to go to Seattle. The car owners should be advised or asked how these things are going to affect them."