You had to see it to believe it. The Caitlin Clark effect is real and it's potent.

INDIANAPOLIS — Caitlin Clark has traffic backed up on Alabama Street for more than three blocks heading south into the parking garage across from Gainbridge Fieldhouse.

It's 6 p.m. Thursday and a crew of workers directing cars have their jobs cut out for them.

Tony Dunkin is used to crowds jamming up the lane he works on level one of the garage, but he has never seen anything like this for an Indiana Fever game and definitely not for a preseason WNBA game.

The cars are packed like sardines, maneuvering around orange cones, clamoring to get their vehicles into a parking spot so they can get themselves into a seat.

"This is what a Pacers game usually does," Dunkin said, "not the Fever. I call it the Caitlin effect."

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Security staff working at a Delaware Street entrance into the fieldhouse are talking about how some fans were waiting outside two hours before the doors opened to pour into the arena. Waiting for a preseason WNBA game. In 2023, the Fever averaged 4,067 fans a game.

"14,000 of them tonight," said Beverly Franklin. "Now, if they can just have a crowd like this for every game, that would be awesome."

Clark said the same thing Franklin said Thursday. But Clark said it a few hours later, after she stacked the stat sheet in a game that helped the Fever beat the Atlanta Dream 83-80 in the team's only preseason home game. Clark said the same thing to the crowd of 14,000, who had roared with every mention of her name during the game and rose to their feet with every shot she took.

"You all were amazing. Thanks for coming out for a preseason game," Clark said as she was interviewed on court after racking up 12 points, eight rebounds and six assists. "I hope you'll keep coming back."

Prior to Thursday's game, Clark said she wasn't sure how big of a deal she would be in Indianapolis. She said she wasn't sure if people would care about her in Indy.

"I didn't know how the transition would really be going from Iowa City to Indianapolis, of how many people would know me and things like that," Clark said on Fever media day. "And honestly, it's not that much different, which is really exciting. I think it just shows the excitement in this city for women's basketball."

Excitement, especially, for one woman who plays basketball.

'It gives me cold chills'

The only person inside Gainbridge on Thursday who got a cheer from the crowd that could even rival the volume of the cheers for Clark was former Pacers player Lance Stephenson, who was at the game in a bright red Fever jacket.

All around the arena, the "Clark Effect" T-shirts were in full force, the beer was flowing and there were actual lines at concession stands, something Terry Cross said he had never seen before at a Fever game, at least not since the season the team won a title in 2012.

"I'm trying not to say the word no sports fan wants to be called, but I will say the Clark bandwagon is full tonight," said Cross of Indianapolis who has been going to Fever games for more than a decade. "With or without Caitlin, this has always been one of the greatest sports to watch."

But even longtime fans conceded the game and the vibe with Clark on board had a wonderful, new feel.

"The crowd is so much more diverse. We have a lot more men, a lot more dads bringing their daughters. That makes me happy," said Nancy Kehlenbrink, who lives in New Castle. "(The Fever) was always here, but we were kind of secondary to all the other teams, all the other sporting events of Indy. And now we're right there at the top with everyone else."

And the Clark effect translates beyond fandom, said Diane Devor of Connersville. It is very real on the court. Devor immediately noticed a different style of play compared to seasons past with Clark on the floor.

"Teamwork. It's unselfish play. They look for the opening and then they share the ball," she said. "They spread the love."

On the court Thursday, NaLyssa Smith led the Fever with 21 points and six rebounds. Aliyah Boston and Katie Lou Samuelson finished with 11 points each. Clark filled in all the gaps and wowed fans who showed up just to see her play.

The gift shop at Gainbridge on Thursday selling No. 22 jerseys and other Fever gear was elbow to elbow and filled with lines. The halls of the arena, no matter what level, were buzzing.

"This is insane," said Lisa Limio, who has been attending Fever games for more than 12 years. "I hate to say it's one person doing all this (Caitlin Clark) but it really is. It gives me cold chills."

'With Clark, we're going all the way'

The Fever's starting lineup Thursday featured five players. Five very good players. Aliyah Boston, the Fever's No. 1 draft pick in 2023, NaLyssa Smith, Katie Lou Samuelson, Kristy Wallace and Clark.

But Clark, who is ranked the fourth most popular basketball player in the United States, got a massive raucous cheer when she was announced at the start of the game. There was an electricity in the building Micheal Hopson hasn't felt before.

"The whole city's coming together around the momentum of (Clark)," said Hopson, a local superfan. "They've got a whole nucleus of new fans, too, young and old."

Hopson calls Clark "a beast" who will only get better each game and who will catapult the Fever.

"Just think about it, this is her rookie year and everybody's talking" he said. "In a couple more years? With the new players she got around her, Boston, all that, it's going to be like dynamite."

Vivan Whitfield took it a step further Thursday with his thoughts on the Clark effect.

"We're going all the way. I don't see anybody getting away from us," he said. "I predict we are going to win the whole thing."

As fans left the building Thursday after the Fever win, they were feeling that same invincible vibe. Cars all over downtown were honking their horns — after a WNBA preseason game.

Inside the parking garage, the same cars that were packed to see Clark play, were packed in a line to leave for nearly 30 minutes.

"I feel like this is a new era of women's basketball," said Sherry Shaw, as she waited in her SUV in the garage. "What I saw tonight? I have to say I didn't believe it until I saw it. The Caitlin Clark effect is real."

Follow IndyStar sports reporter Dana Benbow on X: @DanaBenbow. Reach her via email: dbenbow@indystar.com.

This article originally appeared on Indianapolis Star: It's just one Indiana Fever game, but the Caitlin Clark effect is real