Voters faced a fresh barrage of misinformation Tuesday, the latest development in a voting period that has been marred by misleading narratives across social media.

Twitter removed a post, shared from a screenshot on Instagram, in which a person falsely claiming to be a poll worker in Erie, Pa., said he had thrown out hundreds of Trump ballots. A far-right influencer falsely claimed on Twitter said that the National Guard had been deployed to Philadelphia and other cities to prevent unrest in the case of a Trump victory.

#Stopthesteal, a hashtag associated with alleged voter fraud and a Democratic theft of the election, was used more than 50,000 times, driven largely by right-leaning influencers including Donald Trump Jr. and Ann Coulter amplifying isolated incidents, according to researchers. One video, in which a pro-Trump poll watcher was mistakenly prevented from entering a Philadelphia polling location, racked up more than 287 million likes, retweets and views across Twitter by the afternoon as evidence of efforts to steal the election, according to researchers.

Late Monday, in a tweet Twitter restricted with a label, President Trump said the Supremes Courts recent decision about Pennsylvania mail-in ballots will induce violence in the streets. He added, Something must be done!

Many of the attempts appeared specifically targeted at voters in swing states, particularly in the battleground state of Pennsylvania. Some, like the presidents, intimated that violence could take place. His statements echoed concerns by elected officials and businesses, which boarded up storefronts before Election Day.

My biggest fear is the potential for physical violence that we didnt have in 2016, said Alex Stamos, head of the Stanford Internet Observatory and a former Facebook chief security officer, said on a media call Tuesday morning from the Election Integrity Partnership, a coalition of misinformation researchers that examined the #Stopthesteal hashtag.

The lead up to the 2020 election has been uniquely influenced by social media, particularly because in-person campaigning has been more limited by the global pandemic. Trump and Democratic candidate Joe Bidens campaigns have spent millions of dollars on social media and other targeted advertising in recent weeks.

But researchers have cautioned that domestic disinformation has also taken on an increased power this election, as groups attempt to spread lies online and even the president uses his Twitter account to share misinformation to his more than 87 million followers.

Facebook, Twitter, Google and Google-owned YouTube, collectively have held more than 100 scenario-planning exercises, launched a spate of new policies including prohibitions on premature declarations of victory and calls to violence, and taken unprecedented enforcement actions, according to the companies.

They have come up with detailed plans on how they will flag whether the election is decided or not, partnering with media outlets to attempt to slow the spread of misinformation. Facebook and Google have banned political and social ads with the close of polls Tuesday, while Twitter has banned them entirely.

They are trying to prevent a repeat of 2016, when in the weeks after the election they discovered that their platforms were abused by Russian operatives who successfully showed disinformation to American voters.

The final day of voting culminates a period in which disinformation has been spread beyond just social media, including in text messages, email and old-fashioned mail.

Across the U.S. voters received an estimated 10 million robocalls in recent days encouraging them to stay safe and stay home, according to researchers.

Throughout Election Day, Twitter labeled some posts as disputed and potentially misleading about an election or other civic process, including several #StopTheSteal posts that suggested fraud was rampant. But many of them remained on the site, unflagged, including a tweet by Trump campaign official Mike Roman that said Democrats were keeping TRUMP WATCHERS OUT to steal the race. The post had gained more than 11,000 retweets by early afternoon.

On Tuesday, officials in Erie County, Pa., disputed the claims in the viral post regarding Trump ballots being tossed. The person making the statements does not work in any way with Erie County, the county said on its Twitter account.

The dissemination of misleading narratives was highly centralized, and, in places, took on the characteristics of a game. A post on 8kun, the anonymous image board at the center of the pro-Trump QAnon conspiracy theory, advised the use of particular hashtags, from #Watchyourballot to #VoteInPerson to #Trump2020Landslide. The message illustrated the behind-the-scenes coordination that goes into creating the appearance of an online groundswell.

The presidents tweet about violence in Pennsylvania was labeled by Twitter with a notice that voting by mail and voting in person have a long history of trustworthiness, and that voter fraud is extremely rare. It also took actions to restrict the spread of the tweet. But the tweet had already been retweeted more than 55,000 times before the social media company throttled it, according to the Election Integrity Partnership.

Facebook appended a label to the same post on its site about the security of mail balloting. Still, it received internal pushback from Facebooks own employees saying they should do more, according to internal communications viewed by The Washington Post.

The light touch from the worlds largest social network alarmed David Brody, counsel and senior fellow for privacy and technology at the Lawyers' Committee for Civil Rights Under Law.

Its really important for the platforms to raise up the authoritative sources and algorithmically downlink conspiracy theories and unsubstantiated rumors, said Brody, warning about the possibility that the presidents words could lead to real-world violence.

The #stopthesteal hashtag gained momentum Tuesday as users and right-leaning influencers spread the banned poll watcher video and other isolated incidents of improper practices or glitches at polling locations, according to First Draft News, a nonprofit that focuses on tackling misinformation. Pro-Trump users had previously popularized the #stopthesteal hashtag during the 2018 midterm election, as part of similarly baseless allegations of wide-scale voter fraud. There were also some signs the hashtag had been promoted by bots.

Zignal Labs, a media intelligence firm, said the hashtag went from just a few dozen mentions at 8 a.m. Tuesday morning to more than 2,000 every 15 minutes by 8:15.

The video of a Trump poll worker wrongfully being denied entry to a polling place in Philadelphia went viral on Twitter with that hashtag and commentary around efforts to steal the election. A local polling judge incorrectly told him that his certificate only worked at one location in the city, when in fact it worked at any.

Kevin Feeley, a spokesman for the Philadelphia City Commissioner Lisa Deeley, said the locations judge of election made an honest mistake in preventing the watcher from entering the location, and the commissioners office acted quickly in informing him of the correct rules.

The poll watcher did not re-enter that particular location, but Feeley said he did gain admittance to another polling location in Philadelphia.

Narratives pushing unproven allegations of widespread voter fraud have been circulating on social media for months, including from Trump, his adult sons, and affiliated outlets and supporters. Stories have been taken out of context, such as a claim that ballots which were found in a ditch in Wisconsin were put there on purpose to hurt Trump.

A video clip of Biden that was deceptively edited to make it appear as if he was admitting to voter fraud racked up more than 17 million views over the past week, according to the left-leaning human rights group Avaaz.

That has led to additional concerns about potential manipulated videos surfacing Tuesday and in the aftermath of voting, in attempts to cast doubt on results.

The Washington Posts Drew Harwell, Cat Zakrzewski and Tony Romm contributed to this report.

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