FALLS CHURCH, Va. — The cavernous remains of this H.H. Gregg are, in festive fashion, loosely disguised as a Spirit Halloween store. Its insides are lined with haunted houses and rusty water towers (both made of flimsy cardboard) and robots with leering pumpkin heads. The walls of costumes almost distract from signage of the store’s past life, boasting “Big screens, big selection, big value.”

Beneath the faded outlines of the space’s former name, posters advertise that Spirit Halloween is now open and now hiring. But in less than two weeks, it will all be gone.

This year, Americans will drop about $9 billion in celebration of Halloween, and its carnival of escapism, a chance to flaunt yourself or disappear into someone else. The holiday’s craziness and camp are fun precisely because they are temporary – and so are the stores that sell it to us.

Since the mid-2000s, Halloween spending has ballooned, with big jumps in money spent on adult and pet costumes. Ana Serafin Smith, director of media relations for the National Retail Federation, which has done an annual survey on Halloween spending habits since 2003, said the way we celebrate the day has shifted with the rise of social media. Suddenly, trick-or-treating was just a fraction of the festivities as a glut of adult-oriented events, from bar crawls to costume parades, flooded the scene.

In all categories — costumes (human and pet), decorations, candy — millennials outspend every other age bracket. Halloween is unique because it’s an opportunity to go wild, without the financial pressure of gift-giving associated with other major holidays, Serafin Smith said.

“This is the only time of the year you can be somebody completely different than you are in everyday life,” she said. “And it’s the only time of year where you can purchase things or splurge on yourself minus gift pressure.”

The crowd at Spirit shows the breadth of Halloween’s appeal. Men in suits chuckle at raunchy costumes. Two boys dart through the wig section, one of them squealing as he slides across the tile in slippers that look like furry monster feet. In the makeup aisle, a girl in a skeleton sweater contemplates a pair of fangs, nestled in a miniature coffin. A tired-looking mother, with a baby on her hip, listens patiently while her little boy makes an impassioned argument for why he has to be Harry Potter.

All the while, a ghostly chorus howls “This is Halloween” from hidden speakers.

Pop-ups hit a real estate sweet spot

For the pop-up stores, which capture about 35 percent of the annual Halloween market according to the National Retail Federation, the scramble begins before summer. Their goldmines are the graves of major retailers that have gone under; Toys R Us, Sports Authority, Circuit City often offer ideal homes, with lots of space and high visibility, but the stores aren’t necessarily picky, said Motti Farag, a real estate broker with CBRE. It’s a win for landlords, who get a tenant that will pay higher rent for just two or three months of occupancy.

“They’ll take the tough elbow space no one else wants because they know they’re a destination,” Farag said. “But this year Halloween stores have had better luck than ever, with all those well-located big-box stores that closed.”

The pop-up landscape is dominated by chains that open and close hundreds of stores across the country each fall. Spirit Halloween, owned by Spencer Gifts, is operating more than 1,325 stores this year. Party City’s pop-up, Halloween City, has 250 locations, with a seasonal workforce of 25,000, according to Ryan Vero, Party City’s president of retail.

Although most of the shops open their doors in late summer, Halloween is a holiday of procrastination. Mary Leonard, who has worked at Spirit stores in the region for five years and manages the Falls Church location, said Spirit stores does almost 70 percent of its business in the two weeks before Halloween.

Leonard, 42, said this year – which was supposed to tie last year for highest-ever Halloween spending, according to the National Retail Federation’s survey, has been the busiest she has seen. Every night of the week except Sunday, the store is open until 11 (fliers promise customers can “shop into the dead of night”) and the staff always has to nudge people out when it’s time to lock up.

“We get so busy on weekends that the stores get tore up pretty bad,” Leonard said. “Even when we’re going through and cleaning up a dozen times a day.”

Leonard can attest to the Halloween fervor among adults; half of the store’s costume inventory is for adults. 2018 has also seen a boom in gaming-related costumes, like Kingdom Hearts, Halo, Fortnite, many of which have already sold out. A few days ago, Leonard said, a “grown man” came in and bought a Fortnite Dark Voyager costume. He walked out the door wearing it.

Year-round retailer look to make impact

Seasonal shape-shifting isn’t just for the pop-ups, though. Year-round party and costume stores undergo their own transformations to stay competitive with the big chains and value stores like Target and Walmart.

The corridors of the Crystal City mall are a veritable retail cemetery, with dozens of vacant store fronts and boarded windows. But throughout the barren hallways, skeletons in formal wear point toward Total Fright. For most of the year, the party and costume store goes by a different name: Total Party. But for now, spookiness reigns.

“Adult female bunny,” the owner, Lorzeno Caltagirone, repeats into the phone, as casually as though he’s casually discussing the weather. “Yeah, we have that.”

Caltagirone, 45, got his start with a seasonal costume store in Washington, D.C., before he started Total Party in 2009. Although the store carries costume supplies year-round, he quickly learned that he’d have to make a change to draw customers in.

“People don’t want to go to a party store for Halloween stuff,” Caltagirone said. “They want to see the word Halloween in the name, or something Halloween-related, or else they don’t think you’re legit.”

Caltagirone does half of his annual business during the month of October, and like the pop-up chains, he makes the bulk of that money in the final two weeks before Halloween. He knows he has to make it count.

“If you have one bad Halloween, you might be able to recover,” he said. “But two bad Halloweens could put you out of business.”

In the fall, Caltagirone triples his staff and hires security guards to do crowd control. He blares Halloween music, keeps his store tidy and his shelves stocked. The big chains might have better name recognition, but Caltagirone prizes customer service and an immersive Halloween experience, complete with an ‘enter at your own risk’ spooky zone in the back of the shop (the motion and clap-activated creatures have been known to startle children into sobs).

Total Fright wins a lot of its Halloween clientele from young city-dwellers, who would rather not trek out to the suburbs, where most of the pop-up chains are. It also benefits from people’s last-minute shopping tendencies and the flaws of online shopping, like poor-fitting costumes and unreliable delivery.

It’s not even time for the afternoon rush, but the store is flooded of customers who’ve come for wigs and weapons, gallons of fake blood and just about every variety of spandex and silicone. A woman in a baseball cap asks an employee for a Catwoman costume, adding “only because I have to.”

“Do I need to change my eyes to be a cute devil?” a girl asks her friend as she considers an array of contact lenses, ranging from milky eyed gold to pupil-eclipsing black.

Soon, it will get full enough that people will line up outside beneath the pumpkin-shaped countdown clock, a glaring reminder that the “Witching Hour” is almost upon us.