CHAPTER 16 
COMPARATIVE ADVANTAGE AND PROTECTION IN THE 
UNITED STATES 
WE proceed now to the consideration of some indirect evidence 
on differences in comparative costs; evidence which, as remarked 
in the preceding chapter, is more abundant than that of the direct 
sort. It is derived from the observation and analysis of some 
patent economic facts, and above all from observation of the 
effects of protective tariffs. An examination of the concrete 
effects of protective legislation brings out a wide range of phe- 
nomena which can be explained only in the light of the doctrine of 
comparative advantage, and which in turn serve to give support 
to that doctrine. For my own part, it is prolonged inquiry on the 
working of protective duties in the United States which has con- 
firmed my conviction that the actual course of industrial develop- 
ment and of trade between nations affords a striking verification 
of essential features in the theory of international trade; and it is 
this conviction which in turn has led me to reflect on the impor- 
tance of the general problem of verification, and to search for 
possibilities of similar verification in other directions also. 
The evidence furnished by the development of American indus- 
tries under the influence of tariff legislation is most striking in the 
contrast between the extraordinary growth of some protected 
industries and the marked failure of others to show a growth at all 
corresponding. We have here a set of phenomena which, tho 
commonly discussed quite without regard to the general principles 
of international trade, are in fact clearly related to those prin- 
ciples — confirm them in the main, suggest modifications or qual- 
ifications in some directions, serve on the whole to illuminate and 
clarify the theoretical analysis. And it is no less true that most 
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