Facebook is still leading the U.S. social networking market by far, with 166 million unique visitors in November, according to comScore’s global social networking report.

While Facebook hit a whopping 166 million unique visitors in November, these numbers do not include visitors from mobile phones and tablets which cover a large population of visitors.

The average user spent 6.6 hours per person engaged on the site during the month, an increase of 37 percent in the past year.

Twitter and Linkedin have been jockeying for second place in audience size but for the month of November, Twitter was 2nd at 35.4 million unique visitors, just passing Linkedin’s 35 million.

In the meantime, MySpace sits in 4th with 25 million visitors and has had a steady decline within the past two years.

Below the big timers is and working their way up is Tumblr.com, which now boasts 15.9 million U.S. visitors – an increase of 131% since November 2010, Google Plus at 15.2 million U.S. visitors in November, and Pinterest.com, a site that first came into comScore radar in May 2011 with 418,000 unique visitors, and since then has soared at 4.9 million visitors.

While Facebook remains leader of the social networking market conScore says there’s more room for some other players in the market to emerge and become successful in their own rights.