U.S. Twitter usage surpasses earlier estimates

eMarketer reports in 2009, there will be 18 million American adults who access Twitter on any platform at least monthly. That represents a 200 percent increase over 2008 levels. Usage will reach 26 million U.S. 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 U.S. adult Web users to use the microblogging service via any platform.

In April, eMarketer estimated that there would be just 12.1 million U.S. 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.