The use of Facebook in the U.S. significantly intensified last year, driving up the social-networking site's usage to impressive levels in the country that is its oldest, most mature market, according to comScore.
In December 2009, almost 112 million unique visitors went to the site, up 105 percent compared with December 2008, making Facebook the fourth-most-popular site in the country. On average, 37.7 million people visited the site per day, up 181 percent, and viewed a total of almost 45 billion pages during the month, up 151 percent.
Overall, Facebook users spent almost 28 billion minutes on the site, almost triple the time in December 2008 and giving Facebook a 7 percent share of time spent online in the U.S. in general. Total visits more than tripled to almost 3.1 billion.
Other significant growth metrics: The average visitor used the site 10.4 days in December, up from 7.6 days, and each visitor spent an average of 247 minutes on the site during the month, up 45 percent. Each visitor went to the site 27.4 times on average in December, up 64 percent.
"Facebook reached critical mass in the U.S. a couple years ago at which point its growth began to feed on itself, allowing its momentum to vault it continually higher," wrote comScore analyst Andrew Lipsman in a blog on Thursday.
As Facebook's usage grows by leaps and bounds not only in the U.S. but abroad as well, industry experts, governments and regular users pay more and more attention to its security and privacy features and policies.
Facebook recently attempted to consolidate and simplify its privacy settings but along the way caught flak when it made some profile information public by default, saying it wanted to make it easier for people to find their friends. Facebook later backtracked a bit, reinstating the option for members to hide their list of friends.
This month, CEO Mark Zuckerberg said that the privacy changes were meant as a response to what Facebook considers is a general shift among Internet users toward sharing more things publicly. Some industry observers took his comments to mean that Facebook plans to push ahead with making more member information public by default in the future. Facebook dismissed this interpretation as inaccurate and sensationalistic.
Facebook is also in the process of complying with a set of requirements from the Canadian government, which took issue with some of the site's privacy policies last year, in particular the amount of profile data that third-party applications gain access to when members install them.