The selection of Kamala Harris as the Democratic nominee for vice president — a senator from perhaps the most solidly Democratic state in the union — marks the latest evidence that gender and race have now surpassed geographic balance when it comes to building a ticket for the White House.
By selecting the junior senator from California, a state that Democrats have captured in every presidential election since 1992, Mr. Biden embraced the modern imperatives of Democratic coalition building that have made the days of choosing running mates who could deliver their home states a relic of the past.
Ms. Harris, who is half Black and half Indian-American, is not expected to scramble the electoral map, nor was the Biden campaign looking to do so. The former vice president leads in polls of most of the crucial battlegrounds.
Instead, ever since Black voters resurrected his primary candidacy in South Carolina, Mr. Biden and his campaign team have made the pursuit of Black voters in November a centerpiece of his bid for the White House. And he had said from the start of the process that he would chose a woman as his running mate.
“She is going to be a great motivator for this ticket,” declared Representative James Clyburn of South Carolina, a key Biden endorser.
If Ms. Harris does not put any particular new state into play, Democratic strategists and Biden allies were hoping her spot on the ticket could increase turnout and Mr. Biden’s margins across the map and strengthen his position in states that Hillary Clinton lost in 2016, in no small part because of a drop in votes in African-American communities.
That includes big cities in industrial states that Mr. Trump carried in 2016 — Michigan, Pennsylvania and Wisconsin — where Democrats did not turn out at the same levels as they did for former President Barack Obama, as well as more Republican-leaning states with sizable Black populations, like North Carolina and Georgia, that the Democratic Party has poured resources into in 2020.
“This is 1,000 percent a demographic selection,” said Theodore R. Johnson, a senior fellow at the Brennan Center for Justice, who studies voting behavior among Black voters. He predicted that Ms. Harris would increase Black turnout.
In truth, for all the talk about geographic balance in presidential tickets, it has been decades since that was on the top of the punch list for presidential candidates looking for a running mate. Mr. Biden’s list of finalists this year was evidence of that: Gretchen Whitmer, the governor of Michigan, was one of the few who fit that old model.
“Geography died a long time ago as a decisive factor,” Anita Dunn, a top Biden adviser, said of running mates in presidential elections.
In 2000, Al Gore lost his home state of Tennessee at the top of the ticket. In 2004, John Kerry picked a Southern running mate, John Edwards, who lost his home state of North Carolina. And in 2012, Paul Ryan did not help Mitt Romney in Wisconsin.
“Geographic balance seems to be a thing of the political past with our 24/7 media cycle,” said Scott Reed, who was the campaign manager for Bob Dole’s 1996 bid for president. Mr. Dole chose Jack Kemp of New York as his running mate; they lost New York to Bill Clinton.
Patrick Murray, the director of the Monmouth University Polling Institute, said historical patterns had become increasingly clear. “A vice president doesn’t bring you states,” he said. “The last vice president who brought a state was Lyndon Johnson in 1960.”
Gender and race are another matter, especially in today’s political environment as Democrats seek to prevent Mr. Trump from winning a second term. Mr. Biden had said late in the primary season that he would select a woman as his running mate, and he had been lobbied aggressively for months to select a Black woman.
Many Democrats celebrated the history-making choice on Tuesday. Not only has no Black woman ever been nominated for vice president or president; a Black woman has never served as governor of any state.
“This has sent a lightning bolt of electricity across a base that has been watching and waiting and looking for a reason to be excited about this race,” said Matt Morrison, the executive director of Working America, a labor-backed political group with three million members. “I have a Black mother who is literally through the roof, and she is emblematic of the visceral excitement of the base that drove Barack Obama to the White House.”
The Biden campaign announced that the hour of Ms. Harris’s selection was the single best hour of the campaign in terms of fund-raising. ActBlue, the party’s main online donation-processing site, collected nearly $9 million between 4 p.m. and 7 p.m.
The praise for Ms. Harris’s potential impact came despite the fact that she failed, in her own 2020 presidential bid, to gain much traction among African-American voters, who supported Mr. Biden over both her and the other Black candidates in the contest, Senator Cory Booker of New Jersey and Deval Patrick, the former governor of Massachusetts. And polling suggests that for all the pressure on Mr. Biden from African-American leaders to pick a Black running mate, Black voters were far less likely to consider that a priority in the selection.
Robert Shrum, director of the Center for the Political Future at the University of Southern California, said more than anything the choice of Ms. Harris should address one of the reasons Ms. Clinton lost to Mr. Trump so narrowly in 2016.
“One of the problems in 2016 was a fall-off in the African-American vote in Wisconsin, Michigan and Pennsylvania,” he said.
Democrats also hope that the choice of Ms. Harris will also attract moderates in swing states, particularly in suburban areas where they are counting on increased support from suburban women.
Almost since the start of the 2020 contest, voters and pundits alike have floated that Ms. Harris might be destined to fill the No. 2 slot this year. She was pressed about this so often during her own presidential bid — sometimes to her visible irritation — that she once half-jokingly told reporters that “Joe Biden would be a great running mate” as her vice president.
Mr. Trump himself called Ms. Harris his “No. 1 draft pick” in a news conference on Tuesday.
Terrie Rizzo, the chair of the Florida Democratic Party, said the fact that Ms. Harris was the daughter of immigrants would be far more significant in helping the Biden ticket there than where she was from.
“Geography matters less than it used to in the general scheme of things,” Ms. Rizzo said. “She is the daughter of immigrants. Florida is a state of immigrants.”
Lis Smith, a Democratic strategist who was a top adviser to Pete Buttigieg for his presidential campaign, said that the notion that the selection would affect the electoral map was “the biggest myth of the veepstakes.”
“It doesn’t,” she said. “It hasn’t in my entire lifetime.”
But she said the choice of Ms. Harris was still politically potent. “With all the issues around systemic racism, it’s really important symbolically to have a Black woman on the ticket,” Ms. Smith said. “It’s about understanding the moment that we’re in.”
Reid Epstein and Astead Herndon contributed reporting.