The survey also found that roughly one-fifth of all US heads-of-household have never used email.
"Nearly one out of three household heads has never used a computer to create a document," said John Barrett, director of research at Parks Associates.
"This data underscores the significant digital divide between the connected majority and the unconnected minority that rarely, if ever, uses a computer."
Age and education are factors in this divide. Half of those who have never used email are over 65, and 56 percent had no education beyond high school.
The annual National Technology Scan reports a steady decline in the number of disconnected households when comparing previous years.
Some 29 percent of all US households (31 million homes) did not have internet access at the end of 2006, citing low perceived value.
"Internet connections have slowly increased in US households, but getting the disconnected minority online will continue to be difficult," said Barrett.
"Age and economics are important factors, but the heart of the challenge is deeper. Many people just don't see a reason to use computers."