Justin Knapp, 30, from Indianapolis, has edited Wikipedia at a rate of 385 edits per day, or just over one every four minutes, since signing up in March 2005. Wikipedia founder Jimmy Wales announced the millionth edit on his Wikipedia page yesterday.
Wikipedia, whose editors work on a voluntary basis, removed the option allowing anyone to edit an entry in 2007 after a series of unreliable updates.
Knapp, who has degrees in philosophy and political science from Indiana University, posted on his page: "Being suddenly and involuntarily unemployed will do that to you."
His edits have mostly been about politics, philosophy, religion and popular culture. The user with the second most edits, Neil Edwards from Wales, had around 620,000 edits.
Wikipedia has around 90,000 editors who regularly contribute to the online encyclopaedia.