The findings came as no surprise to NetRatings analyst Peggy O'Neill, who concluded that those who work in factories or at construction sites probably don't have a chance to use the Web while on the job.
"They're more likely to come home and spend time checking email, chatting online, playing games, and visiting stores than someone who has been online all day long," she said.
Nonetheless, the study brings an important side note to the digital divide debate: While many poor Americans still can't afford to buy computers and join the online world, those who do have Net access like it.
"This tells us that the Internet is getting more mass market," O'Neill said. "We still have a digital divide, but when low-income people are logging onto the Internet, they're not saying, 'Ew, there's nothing here for me.'"
The study looked at the amount of time people were spending online from their home computers during the month of June. For her report, O'Neill used a Prizm Internet Targeting service developed by San Diego-based market research firm Claritas.
Claritas groups the U.S. population into 62 groups called Prizm clusters. These groups are based on ZIP codes and neighborhoods where people live.
NetRatings panelists were used for the research. By knowing the panelists' ZIP codes, O'Neill was able to incorporate the Prizm system.
She looked at the home-based Web surfing habits of all 62 clusters and found that the top five Net users were low-income, blue-collar workers who burned about 12 hours online per month.
Chatting on ICQ instant messenger, clicking through Wal-Mart online, and visiting entertainment sites such as Emazing.com were the most popular activities for the top five clusters.
Those who spent the least amount of time online--about seven hours per month--were high-paid professionals who tended to log onto the Net at home for a glance at Charles Schwab's Web site or Boston.com, possibly to check a stock quote or do other quick business, O'Neill said.
"When these people get home, they don't have a great need to surf the Web," she said.
In August, Media Metrix released a survey that found low-income households, or those with annual incomes at or below $25,000, are the fastest-growing group of Net users. That segment, however, is less than 10 percent of the online population, the study found.