By Anne Steele

Big employers including Gap Inc.'s Old Navy, Target Corp. and Warby Parker are telling employees they can take paid time off to volunteer as election workers this fall as they aim to help solve a national poll-worker shortage and offer workers a way to find a sense of purpose.

Power the Polls, an initiative to recruit low-risk poll workers to staff in-person voting locations on Election Day and during early voting in October, has joined with more than 70 companies, including Starbucks Corp. and Patagonia, to connect people who want to volunteer during the election with counties that offer training. Last week the Civic Alliance, the group behind the campaign, said it surpassed its goal of recruiting 250,000 volunteer poll workers through its corporate partnerships and now has more than 350,000 people signed on to help with the election.

Elections experts estimate that 460,000 poll workers will be needed this year because the coronavirus pandemic could keep home many older Americans, who often serve as poll workers. Nearly 60% of U.S. poll workers were over the age of 60 in the 2018 general election, with nearly 30% over 70, according to a Pew Research Center report. The Centers for Disease Control and Prevention considers seniors to be at higher risk for severe illness from the virus, with eight out of every 10 deaths involving adults 65 or older.

The new effort comes as civic activists are tapping American corporations to help boost voter turnout in a highly contentious election year when voter registration has hit a record low and citizens will be voting on more days -- and in more ways -- than ever before. It also comes in the midst of a broader racial and social reckoning that is pressuring some companies to show a deeper commitment to social engagement.

Time To Vote, a corporate coalition that encourages companies to give paid time off to employees so they can vote, launched in the summer of 2018. It had roughly 400 companies signed on by the start of the midterm elections. Today more than 800 companies have pledged to give their employees paid time off to vote.

About half of the states in the U.S. require some amount of time off for employees to vote in elections, according to Workplace Fairness, a policy institute. The U.S. lags behind most highly developed democracies in getting people to the polls. Even though voter turnout hit a 100-year midterm election high in 2018, only half of the eligible population cast a ballot that year, according to a Pew Research Center study.

Patagonia, the California-based clothing and outdoors outfitter, a founder of Time To Vote, began hearing earlier this year from election offices that there would be a severe shortage in poll workers because most are in the older, higher-risk demographic for Covid-19.

"There's a really positive trend in corporate America to recognize that companies should do more than make products or provide services and have a role in taking care of their communities," said Corley Kenna, a spokeswoman for Patagonia. "A lot of Americans still don't vote and voting can be complicated -- this year that's especially true -- and we think the private sector can play a really meaningful role."

Staffing polling locations is just one of the challenges companies are rallying to address during this year's election season. Companies are also disseminating information about how and where to vote, donating personal protective equipment for use at election sites and, in some cases, offering their own buildings as physical locations for voting and ballot drop boxes when traditional locations such as senior centers and schools aren't available this year, said Steven Levine, director of Civic Alliance, a coalition of companies that have committed to supporting employee and consumer engagement.

Advocates for more corporate-backed voter education cite a range of factors that increase the need for such information. Those include a push by many states to expand access to mail-in voting, efforts to encourage more early in-person voting to prevent long lines on Election Day, and lower new-voter registration nationwide caused in part by the coronavirus-driven closure of departments of motor vehicles, where many sign up to vote while renewing driver's licenses, according to Mr. Levine.

"Companies are going to be looked to as trusted sources of info to provide employees and consumers with guidance," Mr. Levine said.

Companies encouraging their employees to volunteer as poll workers -- and some offering paid time off to do it -- include Salesforce.com Inc., Microsoft Corp., Levi Strauss & Co., Uber Technologies Inc. and Blue Apron Holdings Inc. Meanwhile, ViacomCBS Inc.'s Comedy Central and Snap Inc.'s Snapchat are working to mobilize their large, young audiences to get involved.

Target has for years given paid time off to vote. This year it joined with the League of Women Voters Education Fund to create a website with information about the voting process, including how to register to vote and what is on the ballot. It's also giving employees paid time off to volunteer at the polls.

"We've seen such a groundswell of interest from companies in leaning further in," said Nora Gilbert, director of partnerships for nonpartisan voter-assistance organization Vote.org. "There's this reckoning happening in racial and social justice, and there's more scrutiny on companies to walk the walk. This is a way for them to thread the needle and show a deeper commitment to civic engagement."

A Harvard Kennedy School case study found that efforts from companies during the 2018 midterm elections not only increased voter participation but also benefited business.

"In the past it was seen as a corporate risk to engage in discussion around democracy," said Sofia Gross, public-policy manager at Snap and one of the authors of the report. "It's become more normalized, and not doing something around democracy is seen as a risk now."

Write to Anne Steele at Anne.Steele@wsj.com