Productive Capacity, Product Varieties, and the Elasticities Approach to the Trade Balance

Most macroeconomic models imply that faster income growth tends either to lower a country’s trade balance by raising its imports with little change to its exports or to reduce its terms of trade in order to maintain balanced trade. Krugman (1989) proposed a model in which countries grow by producing new varieties of goods. In his model, faster‐growing countries are able to export these new goods and maintain balanced trade without suffering any deterioration in their terms of trade. This paper analyzes the growth of US imports from different source countries and finds strong support for Krugman’s model.