County Races Ending in a Final Flurry : Ballot: Two supervisors will be chosen, including the board’s first elected black member. Among local issues, city voters will decide whether to increase the number of LAPD officers.

Los Angeles County voters today will elect two supervisors and a district attorney, while deciding on a wide range of local issues, including county government reforms, a tax to pay for more police in Los Angeles and the establishment of card clubs at Hollywood Park Race Track and on or near the Queen Mary.

The election is certain to make history.

By Monday, a record 280,000 of the county’s registered 3.7 million voters had cast absentee ballots, according to election officials. Voters have until the polls close at 8 p.m. to return them to any polling place.

In the hottest race, Yvonne Brathwaite Burke and Diane Watson have fought a close battle to become the first black elected to the Board of Supervisors. The two are running in the 2nd District--which extends from South-Central Los Angeles to the Westside--for the seat being vacated by retiring Supervisor Kenneth Hahn. Burke was appointed to the board in 1979 but was defeated for election a year later.

Both campaigns on Monday were preparing to send hundreds of volunteers into the streets for get-out-the-vote efforts. Volunteers from each campaign planned to visit polling places, checking to see if likely supporters have cast their ballots, and if not, calling or visiting their homes or workplaces to urge them to vote.

Both campaigns also planned to send sound trucks through the district, blaring messages urging voters to support their candidates.

Watson spent Monday walking precincts, while her aides were buying air time for last-minute TV ads. Watson has strong labor support. Burke was riding with one of her most important backers--Rep. Maxine Waters--in a caravan through the district. Her campaign manager, Herb Wesson, was working on a flyer showing Burke with Hahn, another key supporter.

In the 4th District, which extends along the coast from Marina del Rey to Long Beach and inland to Diamond Bar, Supervisor Deane Dana, a three-term incumbent, was fighting a strong challenge from Gordana Swanson, mayor of Rolling Hills.

Don Knabe, campaign manager for Dana, said the supervisor was tending to county business most of Monday, but planned a whirlwind of events on Tuesday. Knabe said several hundred volunteers--including probation officers and sheriff’s deputy and firefighter union members--are organized for a districtwide phone bank and door-to-door effort to get voters to the polls.

Swanson was spending her last day campaigning door-to-door and taking her mobile headquarters--a 40-foot motor home--to shopping centers throughout the district. Swanson also had scheduled a series of radio interviews and a get-out-the-vote effort to be staffed largely by union workers backing her candidacy.

Swanson’s election would give women a voting majority on one of the nation’s most powerful local governing boards. Except for the period when Burke served, the five-member board was all white and all male until Gloria Molina won election in 1991 as the first Latino supervisor this century.

Other dramatic changes could be ahead for county government in this year of voter discontent with the political status quo. Proposition B would provide for election of a county executive officer, and Proposition C would enlarge the Board of Supervisors from five to nine members.

The district attorney’s race effectively ended when incumbent Ira Reiner pulled out of the campaign, virtually handing the job to his former chief deputy, Gilbert L. Garcetti. Reiner’s name, however, will appear on the ballot.

The ballot is filled with other local measures. Proposition A would levy an average $12.52-a-year assessment on properties to fund county park projects.

Los Angeles city voters will decide on proposed tax increases to pay for 100 additional police officers and to modernize the city’s emergency communications system. The measures require two-thirds voter approval.

The city’s voters also will cast ballots on a measure to tap Airport Department revenues for general city purposes and to allow the sale of $1.5 billion in bonds for sewer improvements.