Is housing unaffordable? why isn't it more affordable?

This paper reviews trends in housing affordability in the U.S. over the past four decades. There is little evidence that owner-occupied housing has become less affordable. In contrast, there have been modest increases in the fraction of income that the median renter household devotes to housing. We find pronounced increases in the rent burdens for poor households. We explore the low-income rental market, analyzing the importance of changes in the income distribution, and in housing quality in affecting rent burdens. We conclude that zoning and land use restrictions are more important factors driving up rents. We also sketch out some policies that might improve housing affordability