The relentless march by Americans to trade their landline telephones for cell phones is evident in a study released Wednesday by the National Center for Health Statistics. The study estimates that 14.7% of American households had cell-only connections in 2007.

The highest rates of cell-only households were in Oklahoma and Utah, where at least 26% had just cell phones and no landline phones, while only 5.1% of Vermont households were wired-phone free. The report, conducted by the federal Centers for Disease Control and Prevention, covered 2007, and its authors said the national prevalence of cell-only households has likely grown another 5% since then.

The federal agency conducted the survey because use of different types of phones can skew the results of important polls of Americans. "The exclusion of households with only wireless telephones has potential implications for results from health surveys, political polls, and other research conducted using random-digit-dial methods," the report stated. "Indeed, the potential for bias due to incomplete coverage of the U.S. household population remains a real and growing threat to health surveys conducted only on landline telephones."

Other states with high prevalence of wireless-only households were Nebraska (23.2%), Arkansas (22.6%), Iowa (22.2%), and Idaho (22.1%). States with low prevalence of wireless-only households were Connecticut (5.6%), Delaware (5.7%), South Dakota (6.4%), Rhode Island (7.9%), New Jersey (8.0%), and Hawaii (8.0%). The remaining states fell somewhere in between.

The survey also reported that 13.6% of U.S. adults were living in wireless-only households in 2007. "Results show great variation in the prevalence of wireless-only adults across states, ranging from a low of 4.0% in Delaware to a high of 25.1% in Oklahoma," according to the report.

The report noted that telecommunications companies typically rely on regional and state estimates of wireless-only households, which "are not sufficiently accurate" for their purposes.

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