Only 2 per cent of November's traffic to the site, which launched in May, came from search engines.
"The UsVsThem growth was massively driven by Facebook mobile usage," Malcolm Coles, Trinity Mirror's product director, said in a tweet today. "There is a lesson here for us all. News = mobile. Mobile = Facebook."
Coles previously told Journalism.co.uk how UsVsTh3m had focused on the "messaging around quizzes" in order to inspire readers to share their results, as "people like that sense that what they share expresses something about themselves".
The UsVsTh3m growth was massively driven by facebook mobile usage. There is a lesson here for us all. News = mobile. Mobile = facebook.— malcolm coles (@malcolmcoles) December 2, 2013
More than half of November's traffic was a result of the 'Northometer', an interactive quiz that guesses where the user lives in the UK from a range of questions. Nearly 4 million people played the game, which has had more than three million interactions on Facebook and more than 40,000 tweets. At one point, more than 20,000 people were playing the game at the same time.
In a recent post highlighting UsVsTh3m's most popular 'listicles' – strongly visual articles written as a list in the style pioneered by Buzzfeed – the top two influenced traffic for November.
UsVsTh3m was launched as a mobile-first site and in November 57 per cent of users accessed the site from mobiles or desktops. Despite its UK-centric topics, 30 per cent of users came from outside the country.
"This is an amazing achievement by the team to have grown so quickly in such a short space of time and shows the importance of experimentation for publishers," Coles said in a press release accompanying the announcement.
Trinity Mirror is due to launch a new site focusing on socially-sharable data journalism in the coming weeks. The new site, Ampp3d, will try to tell daily news stories in the form of interactives and visualisations rather than written articles.