More than a third of Americans adults surveyed said they own a smartphone. (JO YONG-HAK/REUTERS)

In the center’s first stand-alone examination of smartphone use, it found that 33 percent of users said their phones were smartphones and 39 percent said their phones operate a smartphone platform such as iOS, Android, BlackBerry, Windows Phone or Palm.

Adoption rates were unsurprisingly higher among wealthier users, and the study found that college-educated users, those under 45, and black and Latinos also had above-average adoption rates.

About two-thirds of those surveyed said they used their phones for e-mail and Web surfing on a typical day and a quarter of smartphone users said their phone is the main way they access the Internet.

In fact, about one-third of those who said they use their cell phones as their main device for Internet access said they have cut the cord and have no high-speed broadband connection at their homes at all.

The study also compared the demographics of the major smartphone platforms, finding that African-Americans and young adults are more likely to use Google’s Android platform, while iPhones and BlackBerrys are more popular among the well-educated and well-off.