The report uses data from the Census’ 2013 American Community Survey and the National Broadband Map. Segmenting the country into regions with 100,000 residents, the report found that in the most affluent sectors, 80 to 90 percent of households have internet at home. In the regions with the lowest median income, only about 50 percent do. The map gives a more detailed look at the inequalities of internet use, and income is one of the strongest determining factors. Many rural areas have high adoption rates while poorer urban neighborhoods have low ones. A 90-year-old in the top income quartile is more likely to have an internet connection than a person of any age in the bottom quartile.

Geography plays a role too, and at first glance, the national map seems to paint a picture of rural and urban division. Densely populated regions have higher rates of internet adoption, while large swaths of the rural South and Southwest lag behind. However, the Great Plains and sparsely populated parts of Montana and and North Dakota also have high rates of adoption, and for such a dispersed country, the US does respectably: Norway and Switzerland are the only two members of the Organization for Economic Cooperation and Development with both higher rates of internet use and a larger share of their population in rural areas, according to the report.

This relationship holds true nationally. Both geography and income correlate with internet adoption, but income appears to play a larger role. Going from regions in the bottom quarter ranked by population density to the top quarter results in a 9 percent increase in average internet adoption. But going from the bottom income quartile to the top results in a 24 percent increase.

But when looking at broadband adoption overall, the US places 16th globally. And when you zoom in closer on the map, the divide looks less like one of urban and rural and more like one of class. For example, in several sections of central San Antonio, Texas, less than 65 percent of residents are online, while in sections of the northern suburbs, more than 83 percent are. The central sections are more densely populated but also poorer; the northern sections are more suburban, but wealthier.

The findings fit with what Pew Research Center’s Lee Rainie has seen as well. "Rural areas are less likely to have broadband access, but generally if you’re looking at non-adoption, socioeconomic factors are more determinative than geography," he says. "Income and education are highly correlated with internet use."

Sometimes it’s simply a matter of not being able to afford internet service, Rainie says. The White House report doesn’t look at costs, but a 2010 FCC study found that 36 percent of people who weren’t online cited expense as the main reason. Often, Rainie says, it’s a general unfamiliarity with technology. In the same FCC study, 22 percent of non-adopters cited various forms of uneasiness with the internet, and another 19 percent said it was irrelevant to their lives.

Since 2001, household internet access has gone from 50.6 percent to 74.4 percent. Gains have been greatest among demographic groups that were furthest behind, but inequalities persist. In 2013, the most recent year in the report, 77.4 percent of white households were online, compared to 61.3 percent of African-American ones. Only 43.8 percent of households with less than a high school education were online, compared to 90.1 percent of those with a college degree.

"Income and education are highly correlated with internet use."

"When we first started doing our work in 2000, class distinctions were pretty pronounced, and people were actively talking about digital divides," Rainie says. "Since then, adoption has occurred in every demographic group. But gaps remain. People who live in households with lower incomes and less education, those people are significantly less likely to be online."

Consequently, getting everyone online in the US will be a matter of affordability and education, says Raman Jit Singh Chima, policy director at Access Now. Increasing competition among service providers could help lower costs, he says, and extending the FCC Lifeline phone subsidy to cover broadband would put internet access within reach of more people. (Last month, the FCC began the process of extending the Lifeline program to cover broadband.) Increasing internet access at schools and funding education programs at libraries and community centers would show more people how to get online and why doing so is useful.

"The most successful programs we hear about not only provide access but provide teaching and mentoring and tech support," says Pew’s Rainie. "You need a whole web of support."

The data from the report is available here.