Historically, why did the import-substitution strategy become popular among developing nations?

What will be an ideal response?

This strategy gained popularity throughout the 1950s because, at this time, most developing nations exported agricultural and mineral products-goods that often faced very unstable international market conditions. Moreover, the terms of trade for these nations seemed to be headed on a long-term decline. When a country experiences a decline in its terms of trade, its imports become relatively more expensive in its domestic market, whereas its exports become less expensive in the world market. As a result of these conditions, by the 1950s import-substitutions policies started gaining prominence.