THE SCARIEST, SILLIEST , sugariest night of the year is finally here. Americans take their Halloween pretty seriously, even if many of us don't know exactly why we carve pumpkins, hang fake ghosts, hand out candy, or dress up like something dragged in by a graveyard cat.

As it turns out, we’ve been wearing Halloween costumes for nearly two millennia. But we've added plenty of modern twists to this ancient tradition.

To help you celebrate, we've summoned up that history, as well as a number of fun-size facts.

Halloween Arrives in America

European immigrants brought Halloween to the United States, where different Old World traditions mingled in America's cultural stew. The celebration gained steam with the explosion of Irish immigration to the United States in the 1800s.

It was only a matter of time before politicians got into the act. Anoka, Minnesota, may be home to the United States' oldest official Halloween celebration. In 1920, the city began staging a parade and bonfire to mark the day.

Urban Legends, Poisoned Candy, and Killer Clowns

One of the most persistent urban legends claims that people hand out candy tainted by poisons, needles, or razor blades.

University of Delaware sociologist Joel Best , who conducts extensive research on tainted Halloween candy, says he's been unable to find even one substantiated report of a child dying or being seriously injured from eating trick-or-treat candy.

“Somebody gets a candy bar and sticks a nail through it and puts a picture up on their Facebook page saying, Hey, this is the treat that I got,” Best says. “And then eventually it gets debunked.”

Though these scares inevitably turn out to be hoaxes, Best notes, some years do bring new twists. In recent years, Colorado's legalization of marijuana caused some unfounded concern. “There was a fear that people would pass out edible marijuana and cause children to overdose,” he says, “which, among other things, completely ignores how much edible marijuana costs.”

In 2016, a rash of creepy clown sightings put trick-or-treaters on edge. But, as with other scares, it’s lacking in hard evidence.

“It reminds me of 1982 when the Tylenol poisonings occurred in September, and that led to a lot of speculation that there would surely be a lot of poisoned candy,” Best says. “There may be some clown stuff this year just because of the timing.” (Due to the revamped release of Steven King's "IT")

But even creepy clowns aren't new, Best notes. “One of the things that surprised me is that this has actually happened before. It's just that this one, also, is amped up by social media,” he says. “There have been periodic clown scares not just in the U.S. but in European countries.”

Most Popular Costumes

Wondering who's most likely to show up at your door this year? Expect a nonstop parade of costumed kid crime fighters, according to the NRF survey. Princess costumes are this year's most popular costume among children, while both Batman and Star Wars characters also appear in the top five. Witches, Spider-Mans, and pirates will also be out in full force.

Nearly half of all adults plan to dress up this year; some several million witches are expected to be on the streets and in the skies this Halloween. Many of those adults surveyed also planned to dress as characters from the Avengers (sans Spider-Man), zombies, and pirates. (A new Google effort to chart trending costume searches, the Frightgeist , suggests we'll also see our share of Wonder Women, Harley Quinns, clowns, and unicorns.)

Even though many pets are less than enthusiastic about wearing Halloween costumes, their owners will be dressing them up whether they like it or not. Pumpkin, hot dog, lion, and pirate top this year's list of costumes for our four-legged friends.

Great Gourds

Far from the pumpkin's native roots of Central America, chilly Illinois produces most of the United States' pumpkins.

Illinois produced some 318 million pounds of pumpkins in 2015, followed by California, Ohio, Pennsylvania, and Michigan, the U.S. Department of Agriculture reports. Together, the nation's major pumpkin-producing states harvested almost 40,000 acres of pumpkins in 2015, a haul worth about $90 million.