Hillary Clinton's failure to connect with US voters through a massive investment in social media could lead to a resurgence in more traditional political advertising methods such as newspapers and radio.

Mrs Clinton employed more than 100 people in her digital team and spent tens of millions of dollars targeting millennials with a series of hi-tech messages on Facebook.

But experts said she might have been better off buying newspaper or local TV adverts in the handful of key states she unexpectedly lost.

Older voters receiving their coverage of the election through local newspapers were more likely to vote there.

"Hillary Clinton should get all her money back. It didn't work," said John Geer, professor of political science at Vanderbilt University.