INTERPRETATION 
369 
this would extend the discussion far beyond the limits of tolerance 
—boundaries already far extended. What would be said, if such 
a task were undertaken, would of necessity be partly in repetition 
of material already presented. Accordingly, we shall rest the 
case at this point except for a final paragraph. 
The discussion of the interrelation of business the country over 
during the period 1919-1925, and of the manner in which the 
resources and check transactions of banks fluctuate with its 
changes from year to year, serves to indicate briefly the condi- 
tions in which an explanation of the phenomena, summarized in 
the first pages of Part V, may be found. The market for loans 
and for deposits for the thousands of member banks which, in 
part, go to make up our banking system, consists of overlapping 
territories. These are connected industrially by the purchase, 
sale, and transfer of goods and services, and are financially bound 
together by money and credit transactions. While the parts of 
this market are linked together in the manner indicated, each is 
more or less specialized with respect both to its industrial develop- 
ment and its financial needs. Each district has its own levels of 
banking requirements, and these are registered in geographical 
differentials tending to persist from year to year. Different as 
are these levels in respect to ratios of loans and discounts and of 
gross earnings to earning assets and to interest rates on cus- 
tomers’ paper, for instance, changes originating in local or in 
national causes tend to be felt in all parts of the banking market 
and give rise in banking series to similar yearly trends and com- 
mon correlations, raising them above or lowering them below their 
own levels at the same time. It is the discovery and measurement 
of these and other patterns indicative of a banking system with 
which this study has been concerned, and which in some respects, 
at least, the observations in this chapter help to explain,