Meanwhile, ranks of people age 16 or older turning to pages of printed books fell to 67 percent from 72 percent, the findings indicated.
Overall, 75 percent of US adults read books in one form or another in a slight slip from the 78 percent figure seen late in 2011, according to the Pew Internet and American Life Project.
The growing popularity of e-books was in step with the hot trend in tablet computers, whether they are dedicated reading devices such as Kindles or Nooks or multi-purpose Internet portals such as Apple iPads or Google Nexus devices.
The portion of US adults with some kind of tablet jumped to 33 percent late this year, as compared with 18 percent as 2011 came to an end, according to the Pew study.
Understandably, the number of people borrowing e-books from US libraries also rose, findings indicated.
People in higher education and income brackets were more likely to be e-book readers, as were those between the ages of 30 and 49, according to Pew.
The findings were based on a survey taken between October 15 and November 10.