Combined, Door to Door Organics and Relay Foods serve 63 markets in 18 states.
More than half of Twitter users access the service via mobile devices, Pew Research finds.
13% of adults who are online use Twitter, up from 8% in November, according to a study released today by the Pew Internet & American Life Project, a division of the Pew Research Center.
Additionally, 95% of Twitter users own cell phones and more than half of those say they access the service via their mobile devices, the study finds.
Twitter adoption is particularly high among non-whites, and the gap between use of the microblogging service among whites and non-whites is growing. The research group finds that 25% of blacks and 19% of Hispanics use the service, compared with 11% of whites. In November’s study, 11% of blacks, 5% of Hispanics and 3% of whites said they were Twitter users.
Aaron Smith, the study's author, says the high rates of Twitter use among non-whites is not surprising, as the online population of blacks and Hispanics tends to be younger than the white online population and Tweeting is more common among younger adults, he says. "Also, non-whites are very active when it comes to the use of mobile devices such as cell phones for internet access, and that is also highly correlated with Twitter use."
19% of survey respondents aged 25 to 34 use Twitter, up from 9% in late 2010. Pew says that 14% of respondents aged 35 to 44 use Twitter, up from 8% in November.
Pew based its findings on polls conducted in English and Spanish of 2,277 adult Internet users on landlines and cell phones between April 26 and May 22, 2011.
In the last eight days, Twitter has announced two acquisitions—social networking dashboard service TweetDeck and paid search services vendor AdGrok.