In the biggest union organizing vote ever held in the Washington area, employes of the Woodward & Lothrop department stores voted overwhelmingly yesterday in favor of representation by the AFL-CIO Retail Store Employees Union Local 400.

The vote was 2,407 in favor of the AFL-CIO union, 600 for the Independent Union of Woodward & Lothrop Employes, which now represents the workers and 973 in favor of no union.

Local 400 President Thomas McNutt said the union victory at Washington's biggest department store chain "means the key to the city for us.

"Woodies is the Giant Food of the department store field. Getting Giant was the key to the supermarkets for us. Woodies is going to be the key to cracking the department stores," McNutt said.

Woodward & Lothrup executives could not be reached for comment after the votes were counted by the National Labor Relations Board last night.

The more than 5,000 workers in 14 Woodward & Lothrup stores and two warehouses are the largest private employe group ever organized by a union in the Washington area.

About 400 ballots were challenged during the vote count, but even if all the disputed ballots were voted for no union or the independent, the AFL-CIO union still would have a majority, union leaders claimed.

Under NLRB rules, it will be five days before the voting results are certified as official. Either the company or the independent union could challenge the election during that time.

Union organizer Gary Sauter said the local hopes to begin bargaining with Woodward & Lothrup for a contract before the end of the summer.

The stores' contract with the independent union, which has represented Woodies' workers for the past 20 years, expires on June 30.

McNutt said fringe benefits will be a major demand in the union negotiations." Wages are important, but the people have told us what they're most concerned about is benefits. They'd like to have a better deal on health insurance," he said.

The union made insurance coverage an issue in its campaign, claiming last week that Woodward & Lothrop made a profit an employe insurance programs. That charge was branded "Local 400's latest lie" by Woodward & Lothrop Chairman Edward K. Hoffman.

An affiliate of the AFL-CIO Retail Clerks International Association, Local 400 began its organizing drive at Woodward & Lothrop by simultaneously marching 150 volunteer organizers into all the chain's department stores to distribute union literature and pledge cards.

Nearly two dozen union organizers were arrested by store security guards on trespassing charges in the early days of the drive, and the union sued the company, charging the arrests violated constitutional rights.

While the union was mounting an aggressive campaign, the company kept a low profile. Woodward & Lothrop executives consistently declined to comment publicly on the labour dispute publicly on the labor dispute. Hoffman sent a series of "Dear Fellow Employes" letters to the store's workers, and the company distributed a video-taped message from the chairman appealing to workers' loyalty to the 99-year-old chain.

As one of the last of the locally owned independent department store chains in the nation and one of the most profitable companies in its field, Woodward & Lothrop was a prime target for the union drive.

Although it represents most supermerkt workers in the Washington area, the clerks' union until now had made few inroads in general merchandise retailing here.

The union had contracts with the Korvettes and Memco discount stores and with Raleighs and Syms clothing stores, but has lost organizing drives at Peoples Drug Stores and Drug Fair.

The union also failed in its first attempt to organize Woodies in 1976, and under NLRB rules had to wait until the independent union's contract was about to expire before it could try again.

"We'll have to look at the rest of the field and see where we have the most interest," said McNutt. "It looks like Hecht's is near the top of the list."

Union officials have made it clear that the drive to represent the Woodies' workers would be the first step in an effort to increase their clout in the Washington area.

The independent union at Woodward & Lothrop is the second independent labor group to be ousted in favor of an AFL-CIO affiliate here this year.

Although the election campaign was nominally a three-way flight, the independent union, headed by Natalie Koelling, became little more than a bystander in the battle between the city's biggest store and the AFL-CIO's biggest union.

The retail clerks merged with the Amalgamated Meat Cutters union recently to become one of the powers of the American labor movement, ranking in size just behind the Teamsters Union and United Auto Workers, which are not AFL-CIO members.

The independent union at Woodward & Lothrop is the second independent labor group to be ousted in favor of an AFL-CIO affiliate here this year.

Potomac Electric Power Co. workers voted earlier this year to replace their independent union with the International Brotherhood of Electrical Workers.

Union organizers also have been active recently among Washington restaurants, winning contracts among some of the most expensive eating places in town. Rather than go through the complex NLRB election procedure, the restaurant unions have thrown up blitzkreig picket lines to force a quick settlement.