The authors thank Ryan Israelsen and Marc Joffe for comprehensive historical municipal bond ratings; Zihan Ye for geographic mapping data; Dan Bergstresser, Daniel Garrett, Mattia Landoni, Scott Richbourg, Richard Ryffel, Mike Stanton, Anjan Thakor, and audience members at the Federal Reserve Board, Penn State University, the 2019 SFS Cavalcade, Texas Christian University, the U.S. Securities and Exchange Commission, the 2019 Brookings Institution Municipal Finance Conference, and the University of Georgia for comments and suggestions; and Brian Gibbons and Dan McKeever for research assistance.