Study shows 41.6 per cent of time spent 'just checking my emails'.
Research by Nielsen reflects the enduring popularity of email with Americans, with activity up from 37.4 per cent of time spent in June 2010.
Operator portals remain as the second heaviest activity (11.6 per cent share of time) despite a double digit decline.
They are being run close by social networking, which now stands at 10.5 per cent.
Elsewhere, the accessing of music and video/movies both saw 20 per cent plus increases in share of activity year over year. However, both news/current events and sports destinations saw more than a 20 per cent drop.
This mobile phone based activity is different from web use on computers, where social networks dominate.
Nielsen says Americans spend nearly a quarter of their time online on social networking sites and blogs, up from 15.8 per cent a year ago.
They spend a third their online time (36 per cent) communicating and networking across social networks, blogs, personal email and instant messaging.
Here are some infographics to explain things in friendly visual terms...