A little data exercise on housing affordability

I just had two graduate students here at USC--Sarah Mawhorter and Ray Calnan--find 25th percentile gross rent and 25th percentile income for renters for the 50 largest MSAs in the United States using 2008 American Community Survey Data. If "affordable" means that every household has the opportunity to spend less than 30 percent of gross income on rent, not a single one of the 50 largest MSAs is affordable for renters at the 25th percentile. The least affordable is Miami, where 25th percentile rent-to-25th percentile income is in excess of 50 percent; the most affordable is Kansas City.