The FCC reports that 19 million U.S. residents still lack access to high-speed Internet service, especially in rural and tribal areas.

Even if broadband is available, about 100 million Americans - nearly one-third of the population - still don't subscribe to the service, the agency said in a report on broadband access and adoption released yesterday.

"Because millions still lack access to or have not adopted broadband, the report concludes broadband is not yet being deployed in a reasonable and timely fashion," the FCC said. The gaps in access are "unlikely to close" until the agency puts into place recommendations to provide service to unserved populations laid out in its Connect America plan.

Broadband access improved over last year, when the FCC found that 26 million Americans lacked access to broadband Internet service.

The population that still lacks access to broadband comprises less than 6 percent of the population, with more than 94 percent of Americans able to access some form of fixed broadband service, the FCC said.

Its report was based on data provided by the State Broadband Initiative, Mosaik Solutions, residential subscription information and demographic analysis between June 2010 and June 30, 2011.

This year's report, the commission's eighth, is the first to include extensive information on mobile broadband service. The commission reported conflicting information on access to high-speed wireless service. The State Broadband Initiative reported more extensive availability of the service than Mosaik Solutions, which offered more conservative estimates.

"Our estimates of Americans without access to broadband are greater with the Mosaik data than with the SBI [State Broadband Initiative] data," the FCC said.

According to the state data, 19.7 million Americans lack access to wireless service at the 3 Mbps speed benchmark. By comparison, Mosaik's findings suggest that the number of residents lacking access to 3 Mbps service ranges from 94 million to more than 150 million, depending on whether the analysis includes HSPA+.

The FCC expressed concerns that both state data and Mosaik estimates may "overstate" deployment of high-speed mobile broadband service, given variables on technology, network configuration, spectrum availability and backhaul.