Preliminary results from the NHIS survey conducted by the CDC from July through December of 2008 are in, with an interesting set of findings. Having interviewed the members of 12,597 U.S. households, the survey suggests that the number of homes having only cell phones is now more common than those that have just conventional landlines; 20% compared to 17%. This is a 3% shift in homes relying on mobile over landline phones from the first to second half of 2008.

Although the trend has been evolving for years, the cell adoption rate is said to have been accelerated by the recession. In the first half of 2003, a mere 3% of households were wireless only, while 43% kept to landlines. The survey’s data also hints that 15% of homes have both the traditional wired phone and wireless handsets but take little to no calls on their landlines. In combination with those relying only on cells, basic math implies that 35% of households are in essence only available via mobile phones.

As would be expected, one in three people aged between 18 and 24 live among those cell-exclusive households, and it gets increasingly less common as the members go up in age. You can read more about their findings here.