"Social networking sites have grown more important in recent years as a venue for political involvement, learning, and debate. Overall, 39% of all American adults took part in some sort of political activity on a social networking site during the 2012 campaign.
This means that more Americans are now politically active on social networking sites (SNS) than used them at all as recently as the 2008 election campaign. At that point, 26% of the population used a social networking site of any kind.
The growth in several specific behaviors between 2008 and 2012 illustrates the increasing importance of SNS as places where citizens can connect with political causes and issues:
In 2012, 17% of all adults posted links to political stories or articles on social networking sites, and 19% posted other types of political content. That is a six-fold increase from the 3% of adults who posted political stories or links on these sites in 2008.
In 2012, 12% of all adults followed or friended a political candidate or other political figure on a social networking site, and 12% belonged to a group on a social networking site involved in advancing a political or social issue. That is a four-fold increase from the 3% of adults who took part in these behaviors in 2008."