Northern Virginia's political campaigns, dominated by an expensive, high-profile race for the chairmanship of the Fairfax County board, reach full stride this Labor Day weekend with growth and traffic issues central to many contests.

By the end of Election Day Nov. 3, major changes in local governing boards are possible not only in Fairfax, but also in Arlington, Loudoun and Prince William counties. All seats in the Virginia General Assembly are up for election, and voters across the state will decide whether to have a lottery, just as the District of Columbia and Maryland do.

The dominant local race, between Republican incumbent County Board Chairman John F. Herrity and Democratic Supervisor Audrey Moore, has been under way for almost 16 years, when both were first elected to the county board. Since then, they have been tirelessly laying claim to the ideological poles of Northern Virginia politics.

In Arlington, an inner suburb long since developed and now facing issues of how dense its rebuilding should be, two of five seats will be filled on the County Board. Arlington voters could elect a black candidate, which would be the first time there since the 19th century.

Statewide, no major changes are expected in the General Assembly because only about one-third of the 140 seats are contested, and Democrats are certain to retain control of both houses.

The big state question is the lottery. Political analysts expect the issue to mobilize such constituencies as religious activists and traditionally nonvoting blue-collar workers, and it is hard to predict how or whether they would vote in local and legislative contests they normally would ignore.

The Herrity-Moore election will be not only a climax in a contentious and personal rivalry between two of the region's best-known politicians, but also a referendum on policies that have helped transform the Washington area's most populous locality. Fairfax County has evolved from a residential satellite of the District into a place with many of the advantages and problems of a major city, according to business, civic and political leaders.

Loudoun and Prince William voters do not elect board members or their chairmen countywide, so no races have riveted attention in the fashion of Herrity-Moore.

But in the counties that swing around Fairfax from the Potomac River to the south to Dulles International Airport and beyond to the north, a flood of new voters will force even longtime incumbents such as Prince William Supervisor Kathleen K. Seefeldt (D-Occoquan) to run as though they were political newcomers.

Growth has been a cornerstone issue in Northern Virginia campaigns for at least two decades. But with Fairfax County's population now at 710,000, making it the largest regional locality, and the region's inadequate transportation network nearing a crisis, many believe the growth debate has emerged with greater force and clarity than ever before.

For better or for worse, no public official has been more closely identified with this change than incumbent Herrity, whose bald pate and barrel chest have become familiar features at a stream of ribbon-cutting ceremonies.

For better or for worse, no public official has been more closely identified as a skeptic of the change than the challenger Moore, whose slightly nasal voice sang out "no" votes on key development and public facilities proposals.

The high-profile race represents a quantum leap in scale and sophistication of Northern Virginia politics. In Fairfax, at least, the days when an election could be won solely with a low-cost, door-to-door effort apparently are over.

Herrity and Moore are expected to spend in total between $750,000 and $1 million, making it the most expensive local race in the history of Virginia and the Washington suburbs. Herrity, who is expected to outspend the challenger, will likely take his message to the Washington television stations; Moore may follow suit if she can afford it.

Some of the supervisor district races, which used to be winnable for $20,000 or so, are going to cost the winners at least $60,000, observers estimate.

Yet in an age when political campaigns often are won or lost along party lines on peripheral matters of image and style, the race for the Fairfax chairmanship will likely be waged over issues. Throughout their public careers, Herrity and Moore have defined two agendas for Fairfax County and won constituencies with two sets of grievances and expectations.

"This election makes a difference," said Supervisor Thomas M. Davis III (R-Mason). "It's two different perspectives of what they want the county to be over the next 15 to 20 years."

While Herrity and Moore have sought different ends, they have used remarkably similar means: combative rhetoric, high visibility in the news media and unceasing appearances before civic groups and any other audience with the patience to listen.

Herrity, 55, was elected in 1971 as the county board's only Republican when he won the Springfield district, in the southwestern section of the county. Fairfax's population that year was 471,000. Herrity was elected to the countywide chairmanship in 1975 and has been reelected twice. He ran unsuccessfully for Virginia's 8th Congressional District in 1978.

Herrity became one of the region's most powerful officials by speaking to the grievances of an ascendant class of middle-income suburbanites -- tapping their anxieties about, among other things, rising taxes and recurring crises at the District's Lorton prison complex in southeastern Fairfax.

The chairman also was the most celebrated booster of Fairfax's successful effort to buttress its mostly residential tax base with commercial development. The conversion has brought more jobs and office parks, as well as more traffic jams and higher property tax assessments. Elegant new restaurants at Tysons Corner have come hand-in-hand with splitting new headaches on the Capital Beltway.

These changes have coincided with similar changes in the political landscape and placed Herrity solidly on the defensive for the first time in his public career, according to observers in both major political parties. Instead of turning community anger to political advantage, Herrity is finding that the policies with which he is aligned are themselves a major source of resentment.

Many blame excessive development for the region's exasperating traffic delays. On some sections of Rte. 50 in western Fairfax County, traffic has almost doubled since the last county board election in 1983, according to state highway statistics. A rush-hour commute on this stretch has grown by as much as 30 minutes -- a pattern mirrored in rapidly developing areas around the county.

Although Herrity has downplayed his association with developers -- he has vowed he will not take their financial contributions in his campaign -- recasting his image would be an improbable feat, observers say. His prospects were not helped by a misdemeanor conviction last year for failing to reveal a developer's contribution from the 1983 campaign before a land-use vote.

But if Moore, 58, hopes to take advantage of Herrity's political liabilities, she will also have to fend off attacks. She has represented the Annandale District, in south-central Fairfax, since 1971. From the first, she has inveighed against what she said was too-rapid growth and irresponsible planning. She also has cast votes that may prove unpopular in her current race.

Herrity -- arguing that road construction, not development, is the real issue -- is expected to flail away at such pressure points as Moore's opposition on key votes to the extension of I-66 inside the Beltway, the Dulles Toll Road and the Springfield Bypass.

Moore's outspoken style has made her extraordinarily popular in her district, while giving her a reputation as something of a loose cannon in some county political circles. Recently she has softened her rhetoric.

Two independents, James S. Morris Jr. and Robert T. (Terry) Robarge, are seeking the chairmanship. Morris, 47, is a real estate broker and lives in Herndon. Robarge, 46, is a mortgage banker and lives in Centreville.

The election could hinge on how Fairfax's new voters -- the county has 376,587 registered voters, 27 percent more than in the 1983 election -- respond to Moore's revamped image.

In Richmond, where tax revenues from Northern Virginia pay for a major portion of the state government's annual spending, the political winds in Fairfax County are monitored with special interest. Still unclear is how much support, if any, Gov. Gerald L. Baliles, a popular, probusiness Democrat, will give to Moore in her election bid.

The 1987 election may have even greater significance in Northern Virginia's outer suburbs. Loudoun and Prince William counties are in a situation similar to that of Fairfax County 10 to 15 years ago, many believe.

Officials in those two counties are now confronted with soaring growth and are seeking to limit the negative impact of development, while encouraging business expansion to help pay for the new schools and other services.

While the Herrity-Moore race has enthralled Northern Virginia political observers like no other in recent years, it isn't the only battle on which to keep a close eye. Among the other key contests:

In Arlington, four candidates are seeking two board seats; the top two vote-getters win. The candidates are Democratic incumbent Albert C. Eisenberg, Democrat William T. Newman and Republican-backed independents Dorothy T. Grotos, a former board member, and Jane Bartlett. Newman would be the first black officeholder since Arlington became a county in 1920, and the first black to hold an office in the same territory since 1888.

In the Fairfax Dranesville supervisory district, which includes Great Falls and northwest Fairfax County, incumbent Republican Nancy K. Falck is facing a tough fight to hold her seat. After a relatively narrow escape in last spring's primary, many believe Falck is vulnerable to Democrat Lilla Richards and independent Christian activist Robert L. Thoburn.

In Fairfax's Mount Vernon district, in the southeastern part of the county, Republican Supervisor T. Farrell Egge is facing a strong challenge from Democratic lawyer Gerald Hyland, who lost to Egge in a special election in 1984.

In Fairfax's Springfield District, incumbent Republican Elaine McConnell is considered vulnerable to Democratic challenger Toni Carney. Independent Thomas E. Giska is also making a bid.

In Prince William County, Democratic Commonwealth's Attorney Paul B. Ebert, who has been the county's top prosecutor for 20 years, is in a tough countywide race against Republican Peter W. Steketee, a Manassas lawyer. Ebert, once considered invincible, must contend with a wave of new voters in the county who do not know him.

First-term Prince William Republican Supervisor Tony Guiffre is in a heated race to save his Gainesville District seat on the county board against Democratic real estate agent Robert L. Cole. That race is expected to pit rural activists in Prince William's remote western end against suburban voters around Manassas.

In Loudoun County, four-term Supervisor James F. Brownell, once a Republican, is running an uphill race as an independent for his Blue Ridge district seat after clashing bitterly with county GOP activists last year. Ben F. Fordney, who as a federal worker is required by the Hatch Act to run as an independent, has been endorsed by county Democrats; Larry Johnson is the Republican nominee.

State Sen. Clive L. DuVal II, the powerful dean of Northern Virginia's General Assembly delegation and a Democrat who represents the 32d District centered on McLean, is facing a strong challenge from Republican lawyer Bobbie Kilberg, a former White House aide.