In 2009, there will be 18 million US adults who access Twitter on any platform at least monthly, according to eMarketer. That represents a 200 percent increase over 2008 levels. Usage is predicted to reach 26 million US adults in 2010, a further 44.4 percent climb.
This forecast counts 11.1 percent of Internet users as Twitter users this year, a figure close in line with Harris Interactive and Pew Internet & American Life Project estimates of 13 percent and 11 percent, respectively, in spring 2009. In 2010, eMarketer expects 15.5 percent of all US adult Web users to use the microblogging service via any platform.
In April, eMarketer estimated that there would be just 12.1 million US adult Twitter users this year. The upward revision is due to growth in Q2 2009 even stronger than the huge gains seen by Twitter in Q1.
In June 2009, for example, Nielsen reported nearly 21 million unique visitors to Twitter.com. That was a year-over-year increase of close to 2,000 percent, but also an increase over May 2009. Nielsen, comScore and Compete pegged US unique visitors at 18.2 million, 17.6 million and 19.7 million, respectively, that month.
Because many users access Twitter via text messages, mobile apps and various desktop applications, in addition to Twitter.com, eMarketer’s estimate of 18 million users for 2009 is somewhat conservative. This is due in part to research indicating low levels of engagement among the majority of Twitter users.