Nearly a quarter of Americans are offline, with no experience of the internet, a survey has found.
Literacy levels play a part in keeping Americans offline
The Pew Internet and American Life Project studied the ever-shifting internet population in one of the world's most wired nations.
It found that the digital divide is likely to remain in place as the number of people dropping offline equals the number of new users adopting net technology.
The share of the US population on the internet has hovered around the 60% mark since October 2001 and is likely to remain around that level, the researchers said.
Although 42% of Americans say they do not use the internet, half of them have either been net users at some point or use the web via other family members.
And 17% are now classified as net dropouts, citing technical problems with computers or internet providers as the reason for abandoning their net connection.
My grandfather goes online and loves it and my grandmother wants nothing to do with it
Amanda Lenhart, Pew Internet
This is a rise from the 13% of net dropouts identified by a similar survey in 2000.
Half of non-users say that they do not think that they will ever go online, seemingly having no interest in browsing the web or using e-mail.
This trend tends to be among the poorer, older, female population living in rural areas.
"There are some people who would really rather just be left alone and not forced to go online," said the report's author, Amanda Lenhart.
"My grandfather goes online and loves it and my grandmother wants nothing to do with it."
The cost of computers and internet access is still a major obstacle for a third of non-users. Even more are still concerned about online pornography, fraud and credit card theft.
According to the US Government's National Adult Literacy Survey, up to 23% of the population struggle so much with literacy that they have difficulty completing everyday tasks.
This is likely to be a major barrier to net take-up.