I thank Daron Acemoglu, Pierre Azoulay, Abhijit Banerjee, Pedro Bessone Tepedino, Kent Bradford, Dave Donaldson, Amy Finkelstein, Isadora Frankenthal, Keith Fuglie, Claudia Goldin, Ryan Hill, Josh Lerner, Petra Moser, Nathan Nunn, Ben Olken, James A. Robinson, Karthik Sastry, Heidi Williams, and Samuel Young for advice and comments. I thank seminar participants at MIT, Harvard, HBS, Stanford, Ecole Polytechnique, the London School of Economics, and the NBER Summer Institute (Innovation) for helpful feedback. I am grateful to Laurie Fortis at USDA NIFA for help accessing the CRIS data and to Jewell Little, JoAnna Gorsage, and Stephen Malone at USDA AMS for assistance compiling the Variety Name List in compliance with the FOIA. Anoushka Chopra and Marina Zhang provided outstanding research assistance. The views expressed herein are those of the author and do not necessarily reflect the views of the National Bureau of Economic Research.