The moves come as social network platforms brace for what has been an unusual election cycle due to a high number of mail-in ballots that may cause a delay in final results.
Beginning on election night through the inauguration, Twitter said it would place warning labels such as “official sources called this election differently”, or “official sources may not have called the race when this was tweeted”.
Facebook will add specific information in news feed notifications in its apps and in the labels on posts if a candidate or a party declares premature victory, and will continue to show latest results in its Voting Information Center, it said in a separate statement.
Preparations already underway to challenge U.S. election results
Facebook said it will also monitor a range of issues in real time on Election Day, including reports of voter suppression content, and will remove any attempts to suppress participation or intimidate voters.
U.S.-based accounts with over 100,000 followers and a significant engagement will also be considered for labeling, Twitter said.
Social media companies are under pressure to combat election-related misinformation and prepare for the possibility of violence or poll place intimidation around the November vote.
In an updated blog, Twitter said it would consider state election officials and national news outlets such as ABC News, Associated Press, CNN and Fox News that have independent election decision desks as official sources for results.
Their official Twitter accounts will be exempted from labeling, the company said.
(Reporting by Munsif Vengattil, Elizabeth Culliford and Bhargav Acharya; editing by Patrick Graham, Anil D’Silva and Krishna Chandra Eluri)