Just two-thirds of all Americans over age 16 have read a book in the last year, down from 72 percent the previous year, according to the Pew Internet and American Life Project.
The share of those who had read a book on a tablet, however, grew during the same period from 16 percent to 23 percent.
An increase in device ownership supports the trend. The number of Americans who owned either a tablet computer or e-book reader grew from 18 percent in late 2011 to a third in late 2012, according to Pew.
More library patrons are also borrowing e-books. The share of recent library users who have borrowed an e-book from a library has increased from 3 percent last year to 5 percent this year.
Those in their 30s and 40s were most likely to read on tablets or e-readers. Higher income and more education also made readers more likely to turn to tablets.
The survey sample consisted of more than 2,500 Americans over age 16 who were contacted in October and November.