Twitter Headquarters, San Francisco, United States

Demographics
Twitter is mainly used by older adults who might not have used other social sites before Twitter, says Jeremiah Owyang, an industry analyst studying social media. "Adults are just catching up to what teens have been doing for years," he said. According to comScore only 11% of Twitter's users are aged 12 to 17. comScore attributes this to Twitter's "early adopter period" when the social network first gained popularity in business settings and news outlets attracting primarily older users. However, comScore as of late, has stated that Twitter has begun to "filter more into the mainstream", and "along with it came a culture of celebrity as Shaq, Britney Spears and Ashton Kutcher joined the ranks of the Twitterati."
According to a study by Sysomos in June 2009, women make up a slightly larger Twitter demographic than men — 53% over 47%. It also stated that 5% of users accounted for 75% of all activity, and that New York has the most Twitter users.
According to Quancast, 27 million people in the US used Twitter as of 09/03/2009. 63% of Twitter users are less than 35 years old, 60% of Twitter users are Caucasian, but a higher than average (compared to other Internet properties) are African American (16%) and Hispanic (11%); 58% of Twitter users have a total household income of at least $60K.