The first Labor Day parade was held in September 1882; thousands of workers marched and rallied in Union Square for better workplace conditions and pay.

A century later, the first Wigstock was held in September 1985. One thousand spectators came to Tompkins Square Park to see founder Lady Bunny and other drag queens perform in sequins, sky-high platforms, and big wigs at the park’s bandshell.
Wigstock’s genesis was a little less serious than Labor Day’s: It was conceived by Lady Bunny and friends after a drunken night in 1984 at Avenue A’s Pyramid Club.
An instant, outrageous hit, Wigstock became a Labor Day tradition. By 1990, the crowd swelled to 10,000. If you were stuck in the city that weekend with no friends inviting you out to the Hamptons or upstate, you could always head downtown and get a kick out of the crowds and performers spilling over into the streets.
When the park closed for renovations in 1991, Wigstock moved to Union Square, and in 1994, it relocated to the Christopher Street Piers.
Until 2001, that is, when the last Wigstock took place. In subsequent years it was absorbed into the Howl! festival in the East Village. But it seems that 2009 will be Wigstock-less.
Here’s more Wigstock info and ephemera.