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I study the dynamic effects of changes in trade policy in a multi-country model with firms that make durable and destination-specific investments in exporting capacity. Using Mexican exporter-level data, I show that incumbent exporters to minor trade partners account for a smaller share of bilateral exports than do incumbent exporters to major trade partners, indicating a systematic difference in the persistence of the export decision across destinations. The model is calibrated to capture the positive relationship between exporting persistence and export volume, and predicts that trade liberalizations with minor export destinations deliver higher bilateral export growth than liberalizations with major export destinations. Panel analysis on bilateral exports after free trade agreements is consistent with these predictions, con rming that the model is a useful tool for explaining export behavior. Furthermore, I find that heterogeneity in export churning across destinations is a key driver of aggregate dynamics and welfare gains from changes in trade policy.

We evaluate the aggregate effects of changes in trade barriers when these changes can be implemented slowly over time and trade responds gradually to changes in trade barriers because firm-level trade costs make exporting a dynamic decision. Our model shows how expectations of changes in trade barriers affect the economy. We find that while decreases in trade barriers increase economic activity, expectations of lower future trade barriers temporarily decrease investment, hours worked, and output. Further-more, canceling an expected decline in future trade barriers raises investment and output in the short run but substantially lowers medium-run growth. These effects are larger when the expected reform is bigger. In the data, we find that countries with more trade growth after the General Agreement on Tariffs and Trade (GATT) rounds decreased investment and hours worked in the years leading to the tariff cuts, as predicted by our model.

A large empirical literature has shown that countries that trade more with each other have more correlated business cycles. We show that previous estimates of this relationship are biased upward because they ignore common trade exposure to other countries. When we account for common trade exposure to foreign business cycles, we find that (1) the effect of bilateral trade on business cycle comovement falls by roughly 25 percent and (2) common exposure is a significant driver of business cycle comovement. A standard international real business cycle model is qualitatively consistent with these facts but fails to reproduce their magnitudes. Past studies have used models that allow for productivity shock transmission through trade to strengthen the relationship between trade and comovement. We find that productivity shock transmission increases business cycle comovement largely because of a country-pair's common trade exposure to other countries rather than because of bilateral trade. When we allow for stronger transmission between small open economies than other country-pairs, comovement increases both from bilateral trade and common exposure, similar to the data.