While programs like the Connect America Fund have made access to broadband nearly universal in the US, less than three-quarters of Americans actually use it in their homes. A new study by the Pew Internet and American Life Project found that 30 percent of respondents didn't have a broadband connection at home, and 20 percent had no home internet access at all. This wasn't because it was impossible to get; the White House recently reported that 98 percent of Americans had access to at least basic broadband. Instead, people are declining to sign up because of cost, problems getting online, or a simple lack of interest.

While other factors play a role, internet subscription rates break down largely by age, income, and education level. A full 80 percent of people between 18 and 29 have broadband in their homes, a number that drops to 43 percent for those 65 and older. The class divide is just as sharp: 54 percent of people in households that make less than $30,000 a year subscribe, but that number jumped to 70 percent households making between $30,000 and $50,000 and 88 percent of those making $70,000 or over. Only 37 percent of people without a diploma are connected, but 89 percent of college graduates are.

Older, less educated, and poorer Americans are much less likely to be online

Dial-up internet use is now too small to make much of a difference, but factoring in smartphone use adds another layer to the results. If you consider smartphone access to count as home broadband, the number of unconnected Americans drops significantly: about 10 percent of respondents said they had a smartphone but no internet connection at home. Smartphones also go a long way towards erasing a marked racial divide. White Americans are noticeably more likely than black or Hispanic ones to have home broadband, but when you add smartphones to the mix, those numbers even out. Some non-subscribers also likely use the internet on public computers, though surveys about "using" the internet rather than having a home connection come up with similar numbers.

So why are 20 percent of Americans opting out? In 2010, about half of non-users said they just weren't interested, while 10 percent said it was too expensive and 9 percent said it was too frustrating. Their attitudes aren't mirrored by the majority of Americans, most of whom said that not being online was an impediment to finding jobs, using government services, and learning new things. But many non-users aren't likely to get online any time soon. While internet adoption keeps rising, it's plateaued in recent years, with a sizable gap still offline.