As of May 2013, 70% of American adults ages 18 and older have a high-speed broadband* connection at home, according to a survey by the Pew Research Center’s Internet & American Life Project.

Groups with the highest rates of home broadband adoption continue to be college graduates, adults under age 50, and adults living in households earning at least $50,000, as well as whites and adults living in urban or suburban areas.

“We’ve consistently found that age, education, and household income are among the strongest factors associated with home broadband adoption,” said Kathryn Zickuhr, Research Associate for the Pew Research Center’s Internet Project and lead author of the report. “Many dial-up users cite cost and access as the main reasons they don’t have broadband, but for adults who don’t use the Internet at all, a lack of interest is often the main issue.”

In addition, 80% of Americans have either a broadband connection, a smartphone, or both, the researchers noted. The researchers reported in a previous study that 56% of American adults own a smartphone of some kind.

* “We ask adults who say they use the internet at home:’At home, do you connect to the Internet through a dial-up telephone line, or do you have some other type of connection, such as a DSL-enabled phone line, a cable TV modem, a wireless connection, or a fiber optic connection such as FIOS?'” — Kathryn Zickuhr, “How Pew Research calculates broadband adoption”

UPDATE 8/30/2013 — Added definition of “broadband”