• by Mark Walsh  @markfwal, September 11, 2012

The widely anticipated launch of the iPhone 5 on Wednesday could help turn millions more Americans into smartphone owners. Already, 45% of U.S. adults have made the switch to smartphones, according to the latest data from Pew Research Center's Internet & American Life project. That's up from 35% in May 2011.

Some 34% own feature phones, 15% have no cell phone at all, and 5% say they're not sure if they have a smartphone or not.

The report comes on the heels of an estimate yesterday from Nielsen indicating that more than half (55.5%) of U.S. mobile users own smartphones. The Pew study shows that smartphone users tend to be younger and more affluent than the general population. For example, two-thirds of those ages 18-29 have high-end phones, as do 68% of those living in households earning $75,000 or more.

In terms of gender, about the same proportion of men and women have smartphones, at 46% and 45%, respectively. Blacks and Hispanics are more likely to own smartphones than whites -- at 47% and 49%, respectively, compared to 42% of whites.

People who use smartphones may not be smarter, but they are more likely to be better educated: 61% with college or higher degrees and urban or suburban dwellers, 48% and 49%, respectively, compared to 29% who describe themselves as rural residents.

The results come from a Pew survey of 3,014 adults conducted from Aug. 7-Sept. 6. The survey has a margin of error of plus or minus two percentage points.

A separate study released by the research organization last week suggested that smartphone users have also become more sophisticated about protecting their privacy on devices. Half have erased their phones' search or browsing history, while 30% have turned off location tracking. More than half (57%) of mobile app users overall have removed particular apps or decided not to install because of privacy concerns.