Because housing is durable, the housing supply is slow to adapt to declines in demand. This paper uses long-term vacancy--defined as nonseasonal housing units that have been vacant for an unusually long period of time--to quantify the extent of excess supply in the housing market. I find that long-term vacancy is less than 2 percent of all nonseasonal housing units and accounts for only one quarter of the aggregate increase in nonseasonal vacancy from 2001 to 2011. Thus, at the national level, excess supply is considerably less extensive than indicated by traditional measures of vacancy. However, the stock of long-term vacant housing is concentrated in a small number of neighborhoods that do have appreciably high long-term vacancy rates. Some of these neighborhoods have characteristics suggesting that excess supply is related to overbuilding during the housing boom, while others have characteristics that are symptomatic of persistently weak housing demand.
