According to an analysis published in early 2010 by the Pew Internet and American Life Project, 74% of American adults use the Internet. Since 2006, Pew has found that the proportion of Americans who report going online has remained stable.
Pew noted that this research is not directly comparable to its previous studies because the survey population included Spanish-speaking adults.
Regarding broadband use, Pew found that 60% of Americans have home broadband connections. More affluent individuals were more likely to have access to home broadband.
Finally, Pew found that 70% of African Americans use the Internet and 64% of Hispanics (English and Spanish-speaking) go online. While these statistics regarding Internet access in minority groups are encouraging, a 2009 Internet Innovation Alliance study indicates that less than 50% of Blacks and Hispanics use the Internet on a regular basis.
See the chart below for historical data on U.S. Internet use from Pew (click to enlarge).