Today’s Hitwise press release updated April figures for social networking sites: MySpace still dominates the category with nearly 80% market share of visits to the top 20 sites. US Visits to MySpace increased by 70% from April 2006 to April 2007, while visits to Facebook were up 126% and visits to Bebo were up 184%.

Facebook opened up to accept Internet users without a school affiliation in September 2006. Previously it had been limited to those with a college or high school email address. From September 2006 to April 2007, the market share of visits to Facebook grew by 106 percent.
Beyond looking at marketing share of visits, Hitwise clickstream data can give an indication of the influence of a site. MySpace makes up the largest percentage of upstream traffic for almost all of the other social networks in the above table. One in four visits (24.9% of upstream clicks) to the 19 other top social networking sites came directly from MySpace in April 2007. Facebook accounted for a much smaller 2.85% of the upstream traffic to its 19 competitors in April, but that represented an increase of 185% compared to September 2006.

Facebook’s increase in market share and increased presence in the clickstream of the other networks show that its influence is growing rapidly, and that opening up to the entire Internet audience had a positive effect. It appears that users at other social networking sites are experimenting with Facebook as an alternative site, which may help it attain critical mass among non-collegiate users.