It's a landmark moment in her political career that can be traced back to 1984, during her time at Howard University.
At the time, President Ronald Reagan won re-election in a landslide victory. Steve Jobs introduced the first Macintosh computer. Prince's "Purple Rain" album and movie were released. And a 20-year-old Kamala Harris was an undergrad making a name for herself.
"She was always the one who was very even keeled, not fazed, and not in that 'I don't care way' -- in a focused way," said Jill Louis, one of her sorority sisters at Howard.
When Harris and Louis attended the historically Black university in the early 1980s, Louis said they were "coming of age" during a time when the "possibilities were opening up" not just for women but for all people of color.
"[Our generation] came up after the Civil Rights Act. We came up after the Voting Rights Act," Louis said. "So we believed that the legal barriers were now gone, and now it was about reaching out and grabbing opportunity."
She was known around Howard's campus for "being a woman [who meant] business," according to Dr. Shelley Young-Thompkins, who befriended Harris in her freshman year at the school.
"She and I…would be mistaken for professors because we would have briefcases," Young-Thompkins said.
It was common for students to dress up to go to class at Howard. Rather than wearing jeans or sweatpants, Louis said their generation "felt like if we didn't start right now, that would be problematic for us. So, I think we took ourselves fairly seriously."
Harris was recruited for the Howard debate team by Lita Rosario, who said she can still see the confident undergrad she mentored all those years ago on the Democratic debate stage today.
"A lot of times, when males and females are in...debates or spirited conversations, the men kind of use their physicalness to kind of make their point," Rosario said. "I saw that Kamala...she didn't back down when they did that. She proceeded to make her point. And it's funny because when I look at her on television today, I still see that character in her."
In the second Democratic presidential debates hosted by NBC News, Harris had a defining moment when she pressed former Vice President Joe Biden on his opposition of federally mandated busing as a means of integrating American public schools.
"There was a little girl in California who was part of the second class to integrate her public schools and she was bused to school every day. That little girl was me," Harris said during the July debate.
Harris has said that she might not have become a senator if it wasn't for the opportunities afforded to her through school integration.
Carole Porter, one of Harris' childhood friends, was bussed with her to Thousand Oaks Elementary School in Berkeley, California.
"To be able to be bussed and go into this other environment. It transports you into a whole other little universe," Porter said. "It just expands your mind."
Porter said that she and Harris would take the school bus together between 1971 and 1973. The bus would take them from their working class neighborhood in the Berkeley flats into the more affluent Berkeley Hills. She said she remembers Harris being a happy, talkative kid who also liked to sing.
But Harris was also keenly attentive, Porter said. If the bus driver had to make an announcement, she would calm the students on the bus so that everyone could listen. The same attitude applied when Harris would be in class.
"I remember her...sitting in the front of the circle," Porter said. "She was paying attention; she wasn't talking. You know, some of the kids might be in the back talking… She was listening to the story."
Harris, the daughter of an Indian mother and Jamaican father, learned about race and identity from an early age. Her parents separated when she was 6 years old, and her mother, Shyamala Gopalan, raised Harris and her sister, Maya Lakshmi Harris, "to be great and be who you want to be," said Porter.
"There was nothing given to her. I mean it was hard," Porter said. "She was one to not let anyone tell her who she was."
Gopalan, one of the leading cancer researchers in the country, raised her two daughters "as Black women," Porter said, because "that's what they were...and Kamala really was proud of it."
Being raised by a single mother instilled a "certain amount of grit…and just inner strength" in Harris, said Stacey Johnson-Batiste, who has known Harris since they were about 4 years old.
As Harris joins Biden's ticket, her friends spoke about how proud they are of her.