The Centers for Disease Control (CDC) routinely surveys households; as part of that survey, they include telephone ownership. So, CDC has become one of the more interesting sources on trends in telecommunications, especially the increasing switch to wireless-only. Their latest survey has some interesting data in it. Consider these ... by category, the largest percentage of wireless only households is:
Household structure: Unrelated adults, no children
Poverty status: Poor
Geographic region: South (Midwest close behind)
MSA status: Metropolitan
Home ownership status: Renting
Who would have thought that a landline was a luxury of "not poor" households?
Here's a figure from the report that is interesting, but not surprising to me: