Excerpts from the report Introduction: For over three decades, the United States Department of Agriculture has been studying "what makes prices.'' As we review the many statistical studies made in the Department and elsewhere, two things stand out as most important in explaining the behavior of farm prices: (1) Changes in consumer income; and (2) changes in the supply of farm products. By measuring the effects of these two factors, we can often explain a large part of the price changes that have occurred. Our purpose in this bulletin is to present the more important things we have learned about prices over the last three decades. We have not attempted complete coverage of this vast and complex field. We have tried to describe as simply as possible some measures of the main influences on farm prices and some of the "whys."