Excerpt from the report Preface: This report is based mainly on data obtained from the Census of Agriculture for the period 1939-59. Census data were adjusted, however, in three main respects. First, value of sales (marketings) for all years considered were measured in terms of 1959 prices received by farmers. Second, data on number of farms, value of sales, and acreage for all years were (1) adapted to the 1959 census definition of a farm, (2) corrected for census undercounting, and (3) adjusted to the U.S. Department of Agriculture's aggregate estimates. Finally, farms were grouped by value of sales for various years before 1959, according to the interval limits of the value-of-sales grouping of farms in the 1959 Census of Agriculture.