The most comprehensive series of economic data which we have, except those relating to the volume of payments made through the banks, are the statistics which show the volume of business done by the railways. Like bank clearings and debits, the statistics of freight movements are affected directly by the expansion and contraction of every type of business activity (except the purely financial transactions and the sale of real estate), while they are not affected, as are the banking data, by a multitude of factors which bear no close relation to business activity. It is not strange, therefore, that close attention is paid by students of business conditions to the ebb and flow of railway traffic.
Four classes of railway traffic data have been utilized as business barometers. These are the gross receipts, the idle car figures, the carloadings, compiled by the Car Service Division of the American Railway Association, and the statistics of revenue traffic compiled by the Interstate Commerce Commission.
Idle Cars. The idle car figures are no longer of importance. Before the compilation of carloadings was begun, they were of some value because of their prompt appearance, but they probably have never been very accurate. Moreover, the figures are af-