PHILADELPHIA — On Tuesday afternoon, South Carolina Democratic Party Executive Director Christale Spain produced a stack of signs for delegates to wave during that day’s session of the Democratic National Convention.

Marguerite Willis was drawn to a placard that looked homemade, almost as if it were drawn by a young girl, scribbled in red and blue marker. It only said two words: Girl power.

“I said, ‘I want that sign’” Willis, a delegate from Seventh Congressional District, recalled on Wednesday morning to The Post and Courier. “I said, ‘That’s my sign. That’s why I came here.’”

Willis — a tall, slender woman with close-cropped hair, tortoiseshell glasses and ladybugs embroidered on her shoes — positioned herself in her assigned seat in the Wells Fargo Arena, which is in the front row of the risers and runs flush to the main thoroughfare on the convention floor.

As excitement built around the roll call vote to nominate Hillary Clinton as the party’s presidential nominee, reporters, photographers and other delegates passing through from one point to another stopped to admire the sign. At least a dozen journalists interviewed Willis. Several dozen pictures were taken.

And that’s how Willis and her sign ended up on the front page of Wednesday’s editions of The New York Times, accompanying the headline, “Democrats Make Clinton Historic Nominee.”

Willis isn’t alone in that photograph. Spain, who worked for Bernie Sanders in South Carolina’s primary, is seen standing next to Willis, holding up a sign bearing the Clinton campaign’s iconic logo of the Hillary “H” crossed with a right-pointing arrow. State Sen. Margie Bright Matthews stands on the other side, helping Willis carry the “Girl Power” banner.

“I said, ‘Look, you’re an elected official.’ I said, ‘Stand up here with me,’” Willis said she told Matthews. “‘I’m nobody. But this sign has a life of its own. Stand with me.’

“I know before the night was over that the sign had a power to it,” Willis continued, “that was beyond me, and beyond Margie, and really beyond anyone.”

Willis is a successful antitrust attorney in Columbia, but she has never lost sight of the challenges she faced as a young woman lawyer. She graduated from Stetson University College of Law in 1974 as one of just five women in a class of 150.

“From the beginning, I was never a pioneer. I like to say I was a settler,” she said. “People had gone ahead of me and as I like to say taken the machete to the general. But I always felt it was my job to pave the road and put up the lights for the people who came behind me. I didn’t have to use the machete. There was a little path for me.”

She said she was lucky to work for male colleagues who were allies, who said “not our girl” when Willis confronted gender discrimination in the workplace. She said she had latitude to grow and thrive in a field dominated by men.

“But I never had a woman mentor. I never had anybody to look up to,” Willis said, “and so as many people do, I had thought, ‘well I don’t have to help anybody else.’ But overtime I came to realize I did.”

She has never been to a national convention before, but she came to this one, with the goal of helping Clinton become the first woman to lead a major party ticket.

Throughout the whole day and through the close of the DNC session that night, Willis clutched the sign as if it were a valuable treasure. To her, it was.

Other delegates wanted to take turns holding the sign or at least a corner of it. Willis, of course, agreed, though she never let it out of her sight. It’s now safely tucked away in her hotel room as a precious souvenir. She still doesn’t know where the sign came from or who made it.

“The message of the sign, it’s all about the fact that for so many of us who have worked so long and have been successful, we’ve had our moments, we’ve had our struggles, and for those it’s all about those behind us,” she explained. “This won’t change my life. What happens here doesn’t change my life. But it changes everything for the girls behind me, and that’s why I’m here. And it’s all about girl power, and that’s why the sign last night meant everything to me.

“I think, in some way — and this might sound kind of strange — I think I was meant to hold that sign last night,” she said.

Emma Dumain is The Post and Courier’s Washington correspondent.