NBC News:

The rumor started as a post on X. 

The post published in early April misrepresented federal data from the Social Security Administration to falsely suggest that hundreds of thousands of migrants may have registered to vote in Pennsylvania, Arizona and Texas. One hour later, the tweet got the rocket fuel it needed to take off: X owner Elon Musk reposted it with the comment, “extremely concerning.” 

In less than four days, the false narrative was widely shared on X, Facebook and Instagram. Donald Trump and Georgia Republican Rep. Marjorie Taylor-Greene soon joined in, respectively proclaiming, “What is going on???” and “Are migrants registering to vote using SSN?” By the end of the month, the original tweet and Musk’s had generated more than 125 million views.

All the while, election officials in the three states publicly debunked the claims, and multiple news organizations and a news literacy nonprofit published fact-checking articles providing accurate context. Yet the rumors continued spreading — showing how virulent misinformation is and how casually it can spread on social media.

Under federal laws, only U.S. citizens can vote in federal elections, and states are required to regularly update their voter rolls, or voter registration lists, to remove anyone ineligible.

The X post that triggered this latest wave of migrant voting misinformation used publicly available federal data from the Help America Vote Verification (HAVV) program, which shows the total number of times Texas, Pennsylvania and Arizona requested the Social Security Administration to verify a voter’s identity using their Social Security numbers.

While verification requests are not necessarily a one-to-one tally of people registering to vote, the X post falsely presented such numbers as if they were, suggesting that nearly 1.9 million individual voters registered in such states without a photo identification, only using the last four digits of their Social Security numbers.

The post then states that people present in the U.S. illegally can get Social Security cards with a work authorization. That is not widely the case. In 2021, about 587,000 noncitizens, most of whom were  lawful permanent residents or were granted work permits, received a Social Security number. Noncitizens with Social Security numbers are still banned from voting. A study of the 2016 election conducted by the Brennan Center the following year found “that of 23.5 million votes cast, election officials only found about 30 cases of potential noncitizen voting,” according to The Associated Press. 

Mert Bayar, a postdoctoral scholar at the University of Washington’s Center for an Informed Public, has researched the connections between false claims of noncitizen voting and “rigged election” allegations for the past several years. 

Bayar has found that falsehoods connected to these narratives often gain more traction when “there’s a real crisis behind it,” such as the increasing number of migrants seeking to cross the U.S.-Mexico border. They also often include “misleading cuts of evidence to put [in] some sort of a grain of truth,” he said. 

X did not respond to a request for comment.

Once the falsehoods hit social media, moderators face a difficult game of Whac-A-Mole to keep up with the spread, even after a claim has been fact-checked….