• by Mark Walsh  @markfwal, September 16, 2013

Nearly two-thirds of U.S. mobile users now go online using their phones, up from 31% in 2009, according to the latest data from the Pew Research Center’s Internet & American Life project.

Especially intriguing is that more than a third (34%) of mobile Web users say they access the Internet primarily through their phone. That means 21% of all adult cell phone owners are doing most of their Web browsing on their handsets rather than on a desktop or laptop computer.

Young people, non-whites and those with relatively low income and education levels are most likely to use cell phones as their main Internet device. For marketers, the findings suggest the best way to reach a significant chunk of the online population -- including half of those in the coveted 18-29 demographic -- is through their mobile phones.

“It’s certainly indicative of how quickly these devices have taken on a central role in people’s information lives,” noted Aaron Smith, a senior research at the Pew Internet Project and author of the report, which is based on a survey of 2,252 adults between April 17 and May 19.

When it comes to mobile users overall, 63% said they accessed either the Internet or email on their phones, or both. Given that 91% of Americans are cell phone owners, that means 57% of the total population goes online via mobile. Furthermore, more than half of all adults (56%) now own smartphones, and 93% use them for Web browsing.

The 63% figure is up from 55% a year ago and 47% in 2011. People 18-29 are most likely to go online via mobile, at 85%, compared to 73% of those 30-49 and 51% of those ages 50-64. Only 22% of cell users age 65 are mobile Web users.

Among ethnic groups, African-American cell phone owners are the most likely to access the mobile Web, with 74% doing so, followed by Hispanics (68%), and whites (59%). Almost three-quarters (74%) of college-educated cell owners go online on their handsets, along with 67% of those who have attended but not graduated from college.

Mobile users in households with annual income of $75,000 or higher are much more likely than those in every other income group to be mobile Web users, at 79%. Geographically, two-thirds of city-dwellers and suburbanites go online through their phones, compared to half of rural residents.