• by Erik Sass , Staff Writer @eriksass1, January 17, 2014

There is more evidence that, for whatever reasons -- probably including the invasion of old fogies, the lure of new social networks, and the mercurial nature of youth -- teenagers are indeed leaving Facebook.
 
A new demographic study from iStrategyLabs, drawing on data from Facebook’s social advertising platform, found that the number of Americans ages 13-17 using Facebook has declined 25.3% from 13.1 million in January 2011 to 9.8 million in January 2014, while the number of users ages 18-24 has declined 7.5% from 45.4 million to 42 million over the same period.

As one might expect in light of these figures, the number of Facebook users currently enrolled in high school plummeted by 58.9% from 7.3 million to 3 million, and the number of users currently enrolled in college fell 59.1% from 11.7 million to 4.8 million.
 
Facebook’s overall U.S. user base continued to grow over this period, increasing 22.6% from 146.8 million to 180 million. The biggest gain in percentage terms was among users 55+, up 80.4% from 15.5 million to 28 million. Meanwhile the number of users ages 35-54 jumped 41.4% from 39.6 million to 56 million, and the number of users ages 25-34 increased 32.6% from 33.2 million to 44 million.
 
These results seem to fit with recent figures from Pew. A survey in August 2013 found that 84% of teens and young adults polled said they use Facebook, down 2% from the 86% who said they use Facebook in 2012. Over the same period, the proportion of adults ages 18-29 who use Twitter edged up from 27% to 31%, the proportion who use Pinterest increased from 19% to 27%, and the proportion who use Instagram jumped from 28% to 37%.
 
At the same time, according to Pew, over the last year the proportion of adults ages 30-49 who use Facebook increased from 73% to 79%, while the proportion among adults ages 50-64 increased from 57% to 60%, and the proportion among adults ages 65+ increased from 35% to 45%. The proportion of all online adults using Facebook increased from 67% to 71%.