Housing price bubbles, new supply, and within-city dynamics

Although there is broad recognition that cities differ in their tendency to experience house price bubbles, most studies assume away any possibility of within-city heterogeneity in response to a bubble. We develop a model that suggests that this assumption may be appropriate when markets are rising but can be far from reality on the bust side of a bubble. During a housing boom, new construction and related supply adjustments by developers ensure stable relative prices between low- and high-quality segments of the housing market. On the bust side of a bubble, however, reduced housing starts allow demand-side forces and mortgage default to create pressure for relative prices to diverge across market segments. Absent a change in technology, as markets recover and new construction rebounds, relative prices should revert back to pre-crash levels. Evidence based on 2000–2013 single-family home sales in Phoenix, Arizona supports this modeling framework. Additional evidence also suggests that high rates of mortgage default contributed to divergence in relative prices when markets crashed.