From the earliest days of her childhood, Kamala Harris was taught that the road to racial justice was long.

She spoke often on the campaign trail of those who had come before her, of her parents, immigrants drawn to the civil rights struggle in the United States — and of the ancestors who had paved the way.

As she took the stage in Texas shortly before the election, Ms. Harris spoke of being singular in her role but not solitary.

“Yes, sister, sometimes we may be the only one that looks like us walking in that room,” she told a largely Black audience in Fort Worth. “But the thing we all know is we never walk in those rooms alone — we are all in that room together.”

With her ascension to the vice presidency, Ms. Harris will become the first woman and first woman of color to hold that office, a milestone for a nation in upheaval, grappling with a damaging history of racial injustice exposed, yet again, in a divisive election. Ms. Harris, 56, embodies the future of a country that is growing more racially diverse, even if the person voters picked for the top of the ticket is a 77-year-old white man.

In her victory speech Saturday, Ms. Harris spoke of her mother and the generations of women of all races who paved the way for this moment. “While I may be the first woman in this office, I will not be the last,” she told a cheering and honking audience in Wilmington, Del. “Because every little girl watching tonight sees that this is a country of possibilities.”

Yet what also distinguished her was her personal biography: The daughter of a Jamaican father and Indian mother, she was steeped in racial justice issues from her early years in Oakland and Berkeley, Calif., and wrote in her memoir of memories of the chants, shouts and “sea of legs moving about” at protests. She recalled hearing Shirley Chisholm, the first Black woman to mount a national campaign for president, speak in 1971 at a Black cultural center in Berkeley that she frequented as a young girl. “Talk about strength!” she wrote.

After several years in Montreal, Ms. Harris attended Howard University, a historically Black college and one of the country’s most prestigious, then pursued work as a prosecutor on domestic violence and child exploitation cases. She speaks easily and often of her mother, a breast cancer researcher who died in 2009; of her white and Jewish husband, Douglas Emhoff, who will make history in his own right as the first second gentleman; and of her stepchildren, who call her Momala.

It was a story she tried to tell on the campaign trail during the Democratic primary with mixed success. Kicking off her candidacy with homages to Ms. Chisholm, Ms. Harris attracted a crowd in Oakland that her advisers estimated at more than 20,000, a tremendous show of strength that immediately established her as a front-runner in the race. But vying for the nomination against the most diverse field of candidates in history, she failed to capture a surge of support and dropped out weeks before any votes were cast.

Part of her challenge, especially with the party’s progressive wing she sought to win over, was the difficulty she had reconciling her past positions as California’s attorney general with the current mores of her party. She struggled to define her policy agenda, waffling on health care and even her own assault on Joseph R. Biden Jr.’s record on race, perhaps the toughest attack he faced throughout the primary campaign.

“Policy has to be relevant,” Ms. Harris said in an interview with The New York Times in July 2019. “That’s my guiding principle: Is it relevant? Not, ‘Is it a beautiful sonnet?’”

But it is also this lack of ideological rigidity that makes her well suited for the vice presidency, a role that demands a tempering of personal views in deference to the man at the top. As the vice-presidential nominee, Ms. Harris has endeavored to make plain that she supports Mr. Biden’s positions — even if some differ from those she backed during the primary.

While she struggled to attract the very women and Black voters she had hoped would connect with her personal story during her primary bid, she continued to make a concerted effort as Mr. Biden’s running mate to reach out to people of color, some of whom have said they feel represented in national politics for the first time.

Many witnessed — and recoiled at — the persistent racist and sexist attacks from conservatives. President Trump has refused to pronounce her name correctly and after the vice-presidential debate, he derided her as a “monster.”

For some of her supporters, the vitriol Ms. Harris had to withstand was another aspect of her experience they found relatable.

“I know what I was thrown into as the only African-American at the table,” said Clara Faulkner, the mayor pro tem of Forest Hill, Texas, as she waited for Ms. Harris to address a socially distanced crowd in Fort Worth. “It’s just seeing God move in a mighty way.”

While some members of the political establishment professed outrage at the insults, friends of Ms. Harris knew that her pragmatism extended to her understanding of how the political world treats women of color.

Senator Cory Booker, a colleague and friend of Ms. Harris’s who has known her for decades, said in an interview that some of her guardedness was a form of self-protection in a world that has not always embraced a barrier-breaking Black woman.

“She still has this grace about her where it’s almost as if these things don’t affect her spirit,” Mr. Booker said. “She’s endured this for her entire career and she does not give people license to have entrance into her heart.”

After waiting days for results, Democrats rejoiced in a victory that offered a bright spot in an election that delivered losses to many of their candidates, including several high-profile women.

Representative Barbara Lee, Democrat of California, who got involved in politics through Ms. Chisholm’s presidential campaign, said she always believed she would see the first Black woman at the steps of the White House.