This book could not have been written without the financial support of the American Enterprise Institute's National Research Initiative. We are grateful to the NRI board—Christopher DeMuth, Kim Dennis, and the late James Q. Wilson—for approving this project. We thank NRI director Henry Olsen for his patient and steadfast encouragement of our work.
We are grateful to Alan Auerbach, Leonard Burman, Alex Brill, Julie Anne Cronin, Jane Gravelle, Chad Hill, J. Andrew Hipolit, Emily Lin, Jay Mackie, Susan Nelson, Thomas Neubig, Jim Nunns, Laura Power, Amy Roden, Jason Saving, Dan Shaviro, Andrew Smith, Eric Toder, David Weisbach, and George Yin for helpful comments and to Matt Knittel for providing data. We also thank Laura Harbold for her thorough and diligent work on this manuscript.