Facebook has become the most visited web site in the US, the first time Google has not held the top spot since 2007.

According to internet monitors Hitwise in the week ending 13 March Facebook accounted for 7.07 per cent of web visits, compared with Google’s 7.03 per cent.

“The market share of visits to Facebook.com increased by 185 per cent last week compared with the same week in 2009, while visits to Google.com increased by nine per cent during the same time frame,” said Heather Dougherty, research director at Hitwise, in a blog posting.“Together Facebook.com and Google.com accounted for 14 per cent of all US internet visits last week. “

Facebook was also the most popular site on Christmas Eve, Christmas Day and New Year’s Day, as well as the weekend of March 6-7. The last time Google was not the most popular site was September 2007, when MySpace displaced it.

Facebook’s traffic dipped towards the end of last year but the success of games such as Farmville have boosted traffic significantly.