There's no denying that Facebook's presence is huge. In fact, more than half of all Internet users in the U.S. visit the site at least once a month, according to a new report by the research group eMarketer.
Meanwhile, about 42.3 percent of the entire U.S. population is using the site as recently as this month. eMarketer forecasts that 132.5 million U.S. Web users will use the site in 2011. The 13.4 percent increase means Facebook will reach almost nine in 10 social network users and a whopping 57.1 percent of overall Internet users.
By 2013, 62 percent of Web users and almost half (47.6 percent) of the overall U.S. population will be on Facebook.
However, only 7 percent of the country and 9 percent of Internet users use Twitter. But these numbers are expected to grow since less Americans are on the site and there is more room for growth — while Facebook's broad reach means that its once-dramatic growth rates are over.
About 16.4 million U.S. adults — or 9 percent of the adult Internet population — used Twitter at the end of 2010. Growth is expected to surpass 26 percent this year 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 accessing Twitter and sending out tweets, the report said.