Once upon a time, a princess stood on the stoop of Martha and Gerry Yukevich’s William street house in Vineyard Haven. It was Halloween, and the princess was the first visitor of the night.

Her princess hat was pink and pointed, and had a sash flowing from the top.

And behind the princess, perhaps hoping for a treat of its own, stood a white pony.

“I’ll never forget that,” laughed Martha Yukevich, as she recounted the story of her most memorable trick-or-treater.

But in the grand scheme of things, a pony on William street on Halloween doesn’t seem out of the ordinary.

This is, as one resident described it, the “Times Square of Halloween.” It’s crowded, it draws costumed ghosts and fairies from as near as Spring street and as far as New York city, and it’s the place to be on Oct. 31.

“I don’t know where they come from or how they get here,” said resident Christopher Hall, who lives at the opposite end of the street from the Yukeviches and whose family has been doling out sugary snacks on Halloween since 1985. Where the kids go after reaching the corner of Woodlawn and William remains a mystery to Mr. Hall as well. But he’s prepared for the evening. In one room of his home, a skeleton with light-up eyes (“He needs some work,” said Mr. Hall, of the 20-year-old decoration) sits next to a bowl filled to the brim with bags of Reese’s and Kit-Kats. The general consensus from William streeters is to buy candy off-Island, or you’ll go broke trying to buy enough to keep up with demand.

“It’s worth it,” said Mr. Hall. “It’s our favorite day.”

“You can see how it’d be attractive for little kids and parents,” said Phil Henderson, who lives with wife Carolyn across the street from Mr. Hall. “There’s not much traffic; there are a lot of year-rounders.”

This year, the only traffic on William street on Halloween will be of the foot (possibly hoof) variety. Tisbury police are closing the popular destination to cars from 6 to 9:30 p.m. to ensure the safety of those in search of treats.

“I’m very glad they closed off the street,” said longtime resident Wiet Bacheller. “Sometimes I can barely see across the street because of [all] the people there.”

“[The street] was always pretty popular,” she added, but it wasn’t until the past decade that it became the go-to spot.

Mrs. Bacheller and husband John, both retired teachers, have been on William street since the 1970s, long enough to have seen a second generation of trick-or-treaters — children of their own former students — troop past the traditional line of hand-carved pumpkins up to the porch.

The black-and-orange bag trick-or-treaters receive at the Bacheller home contains not chocolate or caramel but rather a fortune cookie. Mrs. Bacheller is still working hard to dispel the myth that she actually makes the cookies herself (they’re from Chinatown in Boston).

Estimates vary among residents as to exactly how many kids and parents visit William street each year, but they range from 300 too 800. Toddlers and preschoolers come early in the evening, high schoolers trickle by as the night wears on.

It’s not just a holiday for the younger set, however. The grown-up residents of William street see the evening as a chance to socialize with neighbors and see fellow Islanders — particularly those who live in the more rural areas of the Vineyard — who’ve made the trip up for the occasion.

“It’s a very festive time,” said Mrs. Yukevich.