U.S. broadband subscribership increased to 68% as of October 2010, up 4% from a year earlier, according to a report released today from the National Telecommunications and Information Administration and the Commerce Department’s Economics and Statistics Administration. But the report also found that households with lower incomes and less education, as well as African-Americans, Hispanics, people with disabilities and rural residents were less likely to have Internet service at home. That finding is quite similar to what the NTIA found in a similar report last year.

According to the report released today titled “Exploring the Digital Nation,” Asian and white households were more likely than average to subscribe to broadband, with 81% of Asian households and 72% of white households subscribing to the service. Hispanic and black households, with subscribership rates of 57% and 55% respectively, were less likely than average to subscribe to broadband. On the geographic side, the report found that 70% of urban households and 57% of rural households subscribe to broadband.

“Income and education are strongly associated with broadband Internet use at home,” but those factors do not fully determine the results, said U.S. Commerce Department chief Economist Dr. Mark Doms on a conference call with reporters today to announce the new findings. “Differences in socio-economic factors don’t explain the entire gap.”

While the gap between Asian and white households disappears when socio-economic factors are accounted for, other gaps cannot be so easily explained, Doms said. Even after adjusting for socio-economic factors, black and Hispanic subscribership lags behind white subscribership by 11%, while rural subscribership lags behind urban subscribership by 5%.

Last year’s study found similar residual gaps and at that time, Commerce Department officials speculated that those gaps were the result of network aspects—the thinking being that if a person’s friends and relatives are not using the Internet, that person may be less interested in using it.

Whatever the reason for the ongoing gaps, NTIA Administrator Lawrence E. Strickling said on today’s call that it was the government’s job to “provide education and explain why broadband is so important.”

Noting that 80% of Fortune 500 companies only accept job applications on line and that more than 60% of employees use the Internet as an integral part of their job, Strickling said the broadband adoption gap threatens U.S. international competitiveness. The report findings, he said, “indicate that outreach should be targeted to specific populations.”

According to the NTIA/ ESA report, the biggest reasons people do not have Internet access at home are a lack of interest or need (47%), the cost (24%) and the lack of an adequate computer (15%).

“Attacking each of the reasons for non-adoption is the best approach for increasing adoption,” said Strickling.

The data on which the NTIA/ESA report was based was gathered in a survey of more than 50,000 U.S. households conducted by the U.S. Census Bureau.