Web analytics firm Hitwise says Facebook continued to steal more market share of US visits from MySpace in January. However, the report says MySpace still has a commanding lead over Facebook in terms of overall US visits to social networking sites.

Here’s how the latest data breaks down. In January 2009, MySpace’s share of US visits to social networking sites fell to 57% from 60.6% in December. Last January, MySpace’s share stood at 72.5%.

By contrast, Facebook’s share increased to 31.1% in January from 27% in December.  Facebook’s share of US social networking visits was just 15% according to Hitwise a year ago.

Tagged ranked third in US social networking share at 2.3%, flat from December, while MyYearbook held steady at 1.67%. AOL’s Bebo saw a slight uptick in share to 0.8%, though that is down from its levels a year ago.

Hitwise’s data on overall share of visits appears to contrast recent Compete data for January, which showed Facebook with a clear lead over MySpace in US reach. According to Compete, Facebook reached 68.5 million people in the US in January, while MySpace reached just under 60 million.