We explore how firms grow by adding products. In contrast to most earlier work on the topic, our conceptual and empirical framework allows for separate treatment of product innovation (vertical differentiation) and diversification (horizontal differentiation). The market context is Japan's...

"The Cliometrics literature on slave efficiency has generally focused on static questions. We take a decidedly more dynamic approach. Drawing on the records of 142 plantations with 509 crops years, we show that the average daily cotton picking rate increased about four-fold between 1801 and...