Labor Day is 100 years old next Monday. On Sept. 5, 1882, the first parade in honor of working people took place in New York City. It was the idea of Peter J. McGuire, founder of the Carpenter's Union and a member of New York's Central Labor Council.

In 1887 Colorado became the first state to declare Labor Day a legal holiday, and in 1894 President Grover Cleveland signed a bill making it a national one.

Which is why you will not be caught in a traffic jam on the Beltway next Monday but will be lying about enjoying the last, long weekend of summer.

Since labor has done that for you, why not do something for labor?

You could organize a sidewalk parade to remind people of what the day stands for. Commemorate this historic anniversary with banners from the past: Workers of the World Unite; Strike for the Eight-Hour Day; No More Child Labor; Remember the Triangle Waist Company Fire (which took the lives of 142 workers in 1912). Two, Four, Six, Eight To Eat You Must Negotiate

A whole generation has grown up without knowing a world where workers had to fight for the right to organize. To teach them the difficulties of solidarity, give a dinner where everyone is assigned a specific chore.

Make one person head of the Table Setters' Union, put another in charge of the United Salad Makers. Have a Federation of Dish Washers, a Congress of Chefs and the Affiliated Wine Pourers. And, of course, appoint owners who will eat up the profits. You might even (oh, shame) have one or two guests to act as scabs.

Perhaps the Table Setters will decide they are overworked and underpaid and call a strike. But are they strong enough to bring the owners to their knees? They are if they can convince the Affiliated Wine Pourers to join them. Will the Federation of Dish Washers back the strike, or will they clean plates and glasses that have crossed a picket line?

Will the Congress of Chefs combine with the United Salad Makers to form Eats International and control dinner? Lead everyone to the bargaining table first and the dinner table later. The only rule is that the group representing the owners must not pick up their wallets, close down the party and take themselves off to a restaurant. Union Made

All this union activity should, of course, be accompanied by union songs. The AFL/CIO puts out a small pamphlet of labor songs and the Federation's library has several union song books. To obtain the pamphlet (100 free and then 10 cents a copy), write: AFL/CIO, Pamphlets Division, 815 16th St. NW, Washington, D.C. 20006.

The 50 "sing-out-together" songs in the pamphlet include old familiars like "Home on the Range" and "The Sidewalks of New York," plus more strident ditties like Woody Guthrie's "Union Maid" (sung to the tune of "Red Wing"): There once was a union maid, She never was afraid, Of goons and ginks and company finks, And the deputy sheriffs that made the raid; She went to the Union Hall When a meeting it was called, And when the company boys came 'round, She always stood her ground. Chorus: O you can't scare me, I'm sticking to the union, I'm stickin' to the union, I'm stickin' to the union, O you can't scare me, I'm sticking to the union, I'm stickin' to the union, till the day I die. Fruit of Your Labor

Another way to celebrate Labor Day would be to labor in a vineyard. Pack a picnic, gather a group of fellow grape pickers and, as you move among the vines, remember the difficulties of the United Farm Workers in organizing the grape pickers and how some liberals gave up grapes altogether rather than run the risk of eating a nonunion concord.

Provenza Vineyards, 805 Greenbridge Rd., Brookeville, Md., lets customers pick their own grapes on weekends from 8 a.m. to 7 p.m. and on weekdays by special arrangement. The vineyard grows these varieties, listed in order of their ripening: (red) foch, cascade, chancellor, villard noir, chelois and (white) seyval, rayon d'or, vidal, and villard blanc.

They ask that you bring pruning shears to free the grapes from the vine and plastic leaf bags to carry them home. According to the vineyard, 16 pounds of grapes will crush down into a gallon of juice. The grapes are 60 cents a pound when you pick up to 10 pounds, 50 cents a pound for 11 to 25 pounds, 45 cents a pound for 26 to 50 pounds, and 20 on down in price till anyone picking 1,000 pounds pays 25 cents a pound. To make your grape-picking arrangements and to get directions to the vineyard, call 301-774-2310.

Two other orchards where you can pick your own grapes: Moormont Orchard, Rapidan, Va. (703-672-2730 or 1-800-572-2262) and Esdraelon Vineyards, Fawn Grove, Pa. (717-382-4018).

And, if you really want to enter into the spirit of things: When you get home set up plastic wading pools, fill them with grapes and have everyone crush the fruit the old-fashioned way.