• by Gavin O'Malley , Staff Writer @mp_gavin, April 19, 2016

Relying solely on cell phones for Web connections was once limited to the lower socioeconomic strata.

Not anymore.

Nearly one in five (18%) of households with annual incomes of $50,000 to $75,000 were mobile-only last year, according to a new study conducted by the U.S. Census Bureau on behalf of the National Telecommunications & Information Administration. That’s up from just 8% in 2013.

What’s more, 17% of households with annual incomes of $75,000 to $100,000 are now mobile-only -- compared with 8% two years ago -- while 15% of households making more than $100,000 are mobile-only, which is up from 6% in 2013.

In other words, mobile is precipitating a “profound shift in how Americans use the Internet,” Giulia McHenry, chief economist with the Office of Policy Analysis and Development, explains in the new report.

Rather than leveling the playing field, however, the shift “may be opening a new digital divide based on the use of particular types of devices and Internet services,” McHenry warns.

For example, low-income households that used the Internet at home were significantly more likely to depend on a mobile data plan than those with higher incomes. The data shows 29% of online households with family incomes below $25,000 only used mobile Internet service at home, compared with 15% of those households with incomes of $100,000 or more.

Although the proportion of high-income households that exclusively used mobile Internet service at home grew somewhat more rapidly between 2013 and 2015, online households with higher incomes still reply far less on mobile alone for Internet access than those in the lowest income group.

Meanwhile, Americans’ rapid move toward mobile Internet service appears to be coming at the expense of home broadband connections.

Three-quarters of American households using the Internet at home in 2015 still used wired technologies for high-speed Internet service, including cable, DSL, and fiber-optic connections.

However, this represented a sizable drop in wired home broadband use -- from 82% of online households in July 2013 to 75% two years later.

The data also shows that over this same period, the proportion of online households that relied exclusively on mobile service at home doubled between 2013 and 2015, from 10% to 20%.