As too many Americans are well aware, the nation’s current economic climate has resulted in thousands of home foreclosures, leaving many housing units vacant.

So how does this impact the census?

For one, we still have to count the people who vacated these housing units. Many have moved in with relatives or friends. As I’ve talked about before on the blog, these families should be included on the census form where they are temporarily living, if they don’t have another usual residence. To help emphasize that message, we’re doing special advertising outreach in about 32 print and radio markets significantly affected by the foreclosure crisis.

Secondly, we still send a form to the housing unit, even though it is vacant now. Generally speaking, the U.S. Postal Service does not deliver mail to vacant housing units. They return these forms back to us as undeliverable. To be sure these housing units are vacant, we will send census workers to follow-up on these addresses beginning in May. This inevitably adds to the salary costs of the census. Thus, unfortunately, another cost of the foreclosure crisis is that we will spend more money verifying that the vacant homes are indeed vacant. Given our mandate to count everyone in the country, we are obliged to do this.

In the meantime, we’re able to get real-time information from the Post Office on which forms are on their way back to us as undeliverable. Incidentally, subtracting these undeliverable addresses is an important part of calculating the current participation rates across the country.

Please submit any questions pertaining to this post to ask.census.gov