UPDATE: Barry Ritholz sez,
In this case, what she wrote is not technically incorrect, but its very misleading. The lowest this rate has been over the past few decades is 8.5%. So while 11% sounds shocking, it is only somewhat elevated after the worst housing crash in the US since the Great Depression.
The typical data point used to describe vacant homes is the Home Ownership Vacancy Rate. In the US, that number is 2.7% for owner occupied houses and 9% for rental properties, apartments, etc.
The sensationalistic number referenced in the CNBC story (repeated by Consumerist) is not commonly used -- indeed, its towards the end of the Census Bureau release that reports such things.
What it references is the total number of structures that are unoccupied -- this includes a whole laundry list of empty properties -- abandoned old farm houses, (Not sure if vacation properties/second homes are included -- I need to check that). No one usually pays much attention to this number, as it provides very little useful insight.
Welcome to America after the housing bubble, where, according to the census, 11 percent of homes are vacant:
Read the rest “11 percent of American homes are vacant -- UPDATED”
Now to vacancies. There were 18.4 million vacant homes in the U.S. in Q4 '10 (11 percent of all housing units vacant all year round), which is actually an improvement of 427,000 from a year ago, but not for the reasons you'd think.
The number of vacant homes for rent fell by 493 thousand, as rental demand rose. 471,000 homes are listed as "Held off Market" about half for temporary use, but the other half are likely foreclosures.