This paper examines the effect of a tariff on long-run growth and welfare in a two-country innovation-led growth model. We show that although raising the home country’s tariff reduces the growth and GDP of the foreign country, it will backfire by depressing R&D and growth of the home country. The Nash equilibrium tariffs can be positive, and they are larger when the government expenditure is more beneficial to private production and/or when the productivity of innovation is higher. The presence of positive Nash equilibrium tariffs provides a theoretical explanation for why countries have incentives to implement a tariff policy regardless of its negative effect on growth. Finally, the Nash equilibrium tariffs are higher than the globally optimal tariffs, that is, the levels that maximize the joint welfare of both countries.

We set up a dynamic stochastic model of a stylized economy comprising a final output sector (with traditional and modern firms) and an intermediate goods sector. It is shown that market integration reduces the volatility of the rate of return to capital invested in modern firms. The induced portfolio decisions of households lead to a reallocation of capital from traditional to modern firms. Despite the presence of a reverse precautionary saving channel, the growth rate unambiguously increases because of the reallocation of capital. Empirical estimates for OECD countries support the theoretical results.