---- Acknowledgements ----
Glaeser thanks the Taubman Center for State and Local Government at Harvard University, and Gyourko thanks the Research Sponsors Program of the Zell/Lurie Real Estate Center at The Wharton School, University of Pennsylvania for financial support. We appreciate the comments of seminar participants at the University of Chicago, the NBER Summer Institute, and the Federal Home Loan Mortgage Corporation on previous versions of the paper. Graham Elliot and James Stock provided helpful guidance. Andy Moore, Charles Nathanson, and Jon Steinnsen provided superb research assistance. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.