Price reductions and other factors led to 40 percent growth in adoption from March 2005 to March 2006. Over the following year, growth was a more modest 12 percent, the Pew Internet and American Life Project said in a report Tuesday.
"The low-hanging fruit was picked ... so you saw a slowdown understandably going to 2007," said John Horrigan, Pew's associate director for research. "You're left with people who are less-intense Internet users. They are likely to be users who aren't processing a lot of bits per month. They don't have the demand for high speed."
Horrigan, however, said many of the Internet users on dial-up simply can't get high-speed service, particularly in rural areas. About 31 percent of rural Americans have broadband at home, compared with 47 percent for the general population.
The Pew study found gains among blacks. Forty percent of black Americans have broadband in the latest study, compared with 14 percent two years earlier.
Blacks now trail whites in broadband adoption by one year — that is, the percentage of blacks with broadband now is about the same as the percentage of whites with broadband a year ago. In early 2005, the gap was two years.
Horrigan said black nonusers appear to be signing up for broadband as their entry to the Internet, skipping dial-up entirely.
Pew found no gap comparing only Internet users. About 70 percent of both blacks and whites have broadband.
The telephone-based study of 2,200 adult Americans was conducted in February and March 2007 and has a margin of sampling error of plus or minus 2 percentage points.