Twitter research is especially fruitful because about 1 to 2 percent of people who post on Twitter tag their tweets with their exact geographic coordinates. A reasonably competent data miner can therefore code up a county-level map of where Americans tweet “pop” versus “soda,” where they switch from “y’all” to “you guys,” or which states prefer which swear words—all in less time than it took Edmond Edmont to bike from Paris to Marseille.