The statistical study presented in the following pages may be best defined as an attempt to construct, on the basis of available statistical materials, a Tableau Economique of the United States for 1919 and 1929. One hundred and fifty years ago, when Quesnay first published his famous scheme, his contemporaries and disciples acclaimed it as the greatest discovery since Newton's laws. The idea of general interdepence among the various part of the economic system has become by now the very foundation of economic analysis. Yet, when it comes to the practical application of this theoretical tool, modern economists must rely exactly as Quesnay did upon fictitious numerical examples.