FORT MILL -- Frawna Peterson sees herself as a part-time psychologist in her role as manager of House of Fireworks on U.S. 21 in Fort Mill Township.

And this week, Peterson is putting her psychology skills to the test almost full time.

Firework enthusiasts from North and South Carolina are flocking have flocked to York County in search of the best pyrotechnic supplies ahead of Tuesday’s Fourth of July celebration.

When Peterson is talking with a new customer, she’s constantly trying to get an understanding of how experienced they are with an explosive element like fireworks.

Some, she says, are veterans who swing by her store each and every year to create bigger and better effects for their families and friends.

Others need a lot more education before they can handle such a responsibility.

“Some of the questions people ask is like, ‘This is what you hold in your hand?’” Peterson said. “You don’t ever hold anything in your hand. Safety plays a big, big role in making sure the fireworks industry stays operable. It’s just like a firearm, it’s just like driving a car. You don’t hear anybody wanting to make recalls on cars because you have an idiot that’s a driver, you know what I’m saying?”

North Carolina law states residents can’t buy or set off any fireworks that leave the ground. That gives shops just over the state line an advantage on sales. North Carolina residents ritually head south down Interstate 77 before each Independence Day to pick up the best deals.

There are three main brick-and-mortar fireworks stores within a half-mile of each other near Carowinds, which straddles the state line.

Mary Murphy, who works at Davey Jones Fireworks, says store employees have to be quick on their feet because of the increased traffic each holiday season.

“We’re constantly ringing people up because they want to be in and out quickly,” said Murphy, who says people have started filling the store since June 24. “It’s a lot of hard work in a little amount of time. We’re here from early morning till late night, and it’s very hard work.”

Several area store managers say customers have become much more savvy with technology, often creating choreographed performances with the fireworks, using Bluetooth technology or iPhone playlists.

Red Rocket Fireworks sells a “Firefly” mobile launching system, which can sync with lights and music to create a personally designed show.

“It’s bringing even more technology into fireworks displays,” said one manager at the shop. “We’re helping people celebrate, and we’re having a good time with them.”