Facebook Dominates Social Networking, Growth Slows

Facebook users in the United States seem to include more than half of all Internet users, measured by log-ins at least once a month, says eMarketer.

In 2011, 132.5 million U.S. web users will use the site monthly, eMarketer forecasts. That increase of 13.4 percent in the number of users means Facebook will reach nearly 90 percent of social network users and 57.1 percent of Internet users. By 2013, 62 percent of web users and almost half (47.6 percent) of the overall US population will be on Facebook.

But that very substantial penetration also means single-digit U.S. user growth in users after 2011.

Twitter will have higher growth rates, at least in part because relatively fewer online Americans use the microblogging service. By the end of 2010, 16.4 million U.S. adults, or nine percent of the adult Internet population, used Twitter. Growth will surpass 26 percent in 2011 as Twitter reaches 11 percent of Internet users and 16.5 percent of U.S. adult social network users. By 2013, nearly 28 million Americans will be tweeting.

Press Release - eMarketer