Concording U.S. Harmonized System Categories Over Time

Schott thanks the National Science Foundation (grants SES-0241474 and SES-0550190) and the Yale School of Management for research support. We thank Julie Linden of the Yale University Social Sciences Library for generous help in securing the U.S. trade data. We thank Mayumi Hairston Escalante for advice and for generous provision of unpublished Census "new-obsolete" files. The research in this paper was conducted while the authors were Special Sworn Status researchers at the U.S. Census Bureau, Center for Economic Studies. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the U.S. Census Bureau. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.