• by Mark Walsh  @markfwal, January 24, 2011

Facebook's U.S. cost-per-click rates hit a high of $1.76 in mid-November before dropping down to about $1.20 by mid-January, according to data from Inside Facebook. Canadian rates hit $1.34. The ad rate peaks near year's reflected higher advertiser demand during the holiday season. Facebook had a total of 145 million North American users as of Jan 1, 2011.

"With around half of the American and Canadian populations now on Facebook, it's still too early to tell if the site is nearing its saturation points in these markets, or if there is still room to capture the half that is still unclaimed," according to an Inside Facebook blog post today. But with traffic for the region hovering around 140 million for the last several months, the site notes that as the market matures, Facebook may face diminishing returns to bring new users on board. Facebook's 2010 ad revenue has been estimated at about $2 billion. Read more here.