Now organizers are trying to turn that burst of digital enthusiasm into traditional get-out-the-vote efforts like phone banking and door knocking. They've created a loose constellation of volunteer networks operating independently of the Harris campaign, all geared toward marshaling local or online communities behind the vice president.

People are sending postcards, texting friends, canvassing battleground states, making friendship bracelets with campaign messages, and sometimes surprising themselves by getting involved in ways they've never done before.

The question is whether the Zoom meetings that drew so much attention during the summer -- for Black women, Black men, white women, white dudes, cat ladies, Taylor Swift fans and more -- will turn out to be a short-lived phenomenon or a powerful catalyst for Harris to beat Republican nominee Donald Trump.

"I think these groups are going to help us win," said Jaime Lopez, the Harris campaign's director of digital coalitions. "They're helping us mobilize and engage people in a way that we haven't seen before, and they're crucial to our path to victory."

Zooms attracted some volunteers for the first time

Mary Catherine Tipton, 33, joined a Zoom call that was organized for white women, swept up in the excitement around Harris' surprise candidacy. There were 164,000 participants, an experience that the Maryland resident described as "inspirational."

"We've got this privilege," she recalled feeling. "We've got this opportunity."

A former teacher in Nashville, Tipton thought about her students who had undocumented family members. After Trump beat Hillary Clinton eight years ago, they asked her "are my parents going to be home when I get home?"

Tipton had been shocked by the outcome of that election -- "how could this happen and I had no idea?" -- and she didn't want to feel that way again.

"I'm going to do something scary," Tipton decided. "This is out of my comfort zone, but that's what we need."

She started by messaging her bridesmaids about the election. Now the group text has expanded to include sisters and other friends. Sometimes they write letters to undecided voters.

Then on a recent Sunday she was in York, Pennsylvania, wearing a campaign shirt and holding a clipboard as she went door-to-door talking to residents. Only a few people answered.

"If my work moves the needle even a little bit, I'll be happy," Tipton said.

A Zoom for Black women lit the spark

The chain reaction that led to people like Tipton volunteering for the first time began on July 21, which was the day that Biden dropped out of the race and endorsed Harris. It happened to be a Sunday, which is when consultant and investor Jotaka Eaddy had been hosting regular Zoom meetings as part of her organization Win With Black Women.

The calls began four years ago to support Black female politicians like Harris, and usually there were hundreds of participants. When Harris became the candidate, everyone wanted to join.

There were so many people, Eaddy struggled to log into her own meeting. When it filled up, she said one member of the group began working her contacts at Zoom to get the company to unlock additional capacity. Eventually there were 44,000 people online and more watching on other streaming platforms.

It was a pep talk, campfire and telethon. People prayed and sang. Comments came so quickly they flickered on the screen -- rows of hearts, "amen," "let's go!" Star Jones shared a donation link and announced near the end of the call that they raised more than $1 million.

The event showcased the fervent support for the vice president at a time when some party leaders were still wondering whether to hold a lightning round primary to choose a replacement for Biden.

"The only conversation we wanted to have was Kamala Harris," Eaddy said.

Another Zoom was held the next day with Black men, and 54,000 participants showed up and raised $1.4 million.

On the following day, gun control activist Shannon Watts woke up before sunrise and started thinking about organizing a call for white women. "Who's in?" she posted on social media that morning.

"And then I just started getting calls from people," Watts said.

More than 164,000 people logged on two days later. When it was over, the progressive advocacy group Indivisible started reaching out to participants to get them more involved and hosting regular Zooms called Women Wednesdays for Harris.

Leah Greenberg, a co-founder of Indivisible, said the virtual meetings have been a starting point for people who might not otherwise participate in the campaign.

"We want to try to keep them engaged," she said. "We want to make sure they're not just going to one Zoom."

Harris supporters have found community through Zooms

Rachel Roberts is one of the people who took that to heart. She described the white women Zoom as a "wake up call" to prevent Trump from returning to the White House, and she was so excited that she donated twice during the meeting.

Roberts had been involved in politics before -- she remembers helping out at a Democratic campaign office as an elementary school student in 1984 -- but never as much as this year.

On Wednesdays, she gathers with other Harris supporters at her local Democratic Party office in Benzie County, Michigan, where they have wine and cheese and watch the Zoom meeting together.

"We laugh, we cry, we get fired up," she said. "It keeps the momentum going."

Sometimes they write postcards or use an app to locate voters to contact. Supporters have made homemade buttons and bead bracelets.

"It's a game of inches right now," said Roberts, 50, who works for an education nonprofit.

Some affinity groups are targeted to different communities, like Taylor Swift fans. They organized "Swifties 4 Kamala" and send out a regular newsletter called "Paint the Town Blue," a reference to one of her songs.

"Time is running out, so we've got to speak now," the newsletter said last month. The group said members have made more than 370,000 phone calls and sent 5.5 million texts about the election.

Annie Wu Henry, a digital strategist who helps lead the organization, said these efforts are a more effective way to reach voters at a time when lots of people have tuned out politics.

Traditional outreach, she said, can feel "much more transactional."

"This is building something that will hopefully last long after that," Henry said.

The Harris campaign has embraced the Zoom groups

The unofficial Zooms drew some mockery over the summer. But Harris' team recognized them as a potential powerhouse and started communicating with the leaders to keep them updated on volunteer opportunities and campaign developments.

Oprah Winfrey brought many of the groups together for an event with Harris near Detroit on Sept. 19.

"I cannot tell you what it means to me," Harris told the organizers behind the scenes. "There's so much about our campaign that is really about fighting against forces that are trying to divide us."

She added, "You are showing that this is what the people want."

Eaddy said the moment "gives me hope for our country and the future."

The Swifties even gave her some beaded friendship bracelets with her name, "Unite for America," and "Win With Black Women." She wears at least one of them every day.

"This is very real," Eaddy said. "It's extremely powerful."