The Geography of a Tweet
A team of researchers lead by GDELT co-creator Kalev Leetaru gained access to the Twitter decahose last October and November and examined 1.5 million tweets from 71 million users.
Among the many things they parsed from the two terabytes of data was the average physical distance between an original tweet its retweet: Some 749 miles (1205 km).
For @ mentions, the average distance between one user referencing another when exact geolocation is known is 744 miles (1197 km).
The paper, Mapping the Global Twitter Heartbeat: The Geography of Twitter, also includes the geographic difference between mainstream news media and news items from Twitter:
Mainstream media appears to have significantly less coverage of Latin America and vastly better greater of Africa. It also covers China and Iran much more strongly, given their bans on Twitter, as well as having enhanced coverage of India and the Western half of the United States. Overall, mainstream media appears to have more even coverage, with less clustering around major cities.
Image: Detail, Network map showing locations of users retweeting other users (geocoded Twitter Decahose tweets 23 October 2012 to 30 November 2012), via FirstMonday.org. Select to embiggen.