People get a real sense of their online neighbors through the trending topics that Twitter and third-party sites publicize, Thurston said.
Among the "hashtaggery" contributed by black Twitter users, he listed #blackis, #blackain't, #uainthittinitright, #santawasblack and #ripbig.
Angela Conyers-Benton, founder and publisher of the tech news site Black Web 2.0, said the first time urban terms -- "BET Awards," "Beyonce", "Ne-Yo," "Jamie Foxx," "Mary Mary" -- trended on Twitter was during the BET Awards last June.
"Because it was the first time something urban had trended on Twitter, then all of a sudden it brought the 'Where did all these black people come from [messages],'" she said. "They were already there before. But you network with who you want to, so people weren't really aware of it."
But she said the trending BET terms sparked a racist reaction from some Twitter users, including a Tumblr site OMGBlackPeople.Tumblr.com (which is no longer active) and the Twitter account @omgblackpeople.
Conyers said that in addition to the demographic reasons for Twitter's popularity among black users, the site may be more popular among African-Americans because as opposed to the "walled garden" of Facebook, Twitter is more open and similar to MySpace.
Referencing social media research that has shown that MySpace is more popular among black and Latino teens, while Facebook is more popular among white and Asian teens, Conyers said, "With MySpace, there was a lot more functionality so people did use it more as a communication tool or a promotional tool. People are using Twitter in the same way."
But as Twitter continues to extend its international reach, some trend watchers on Twitter say that they don't expect African-American tweeters to necessarily maintain their online influence.
"I'm expecting that to probably decrease as Twitter goes gangbusters globally," said Ingo Muschenetz, CEO of What The Trend, a Web site that tracks and explains trending topics on Twitter.
Since the beginning of the year, he said he's seen more international terms break into the trending topics on Twitter.
For example, as Koreans have come online, he's seen more Korean Boy bands lead trending topics. As Indonesians have joined Twitter, he's seen trending terms in Bahasa Indonesia, the national language.
Each time, he said, more experienced tweeters seem surprised by the arrival of the new kids on the block.
"As new groups come online, they start becoming really sort of influential," he said. "And other people will respond and react to that."