Twitter Users Grow, Facebook Slows

The number of Twitter users is accelerating in the U.S., increasing by 31.9% in 2011 to about 24 million microbloggers, compared with a 23.5% growth in 2010, according to market research company eMarketer Inc.

Meanwhile, Facebook Inc., with a much larger base of about 133 million U.S. users at year’s end, experienced a 13.4% growth rate in 2011, down from a 38.6% surge the previous year.

Emarketer said Twitter’s growth rate also will begin to slow this year, but still remain nearly four times higher than Facebook’s growth rate through 2014.