Import tariffs tend to be higher on final goods than inputs, a phenomenon referred to as tariff escalation. Despite its salience, existing research does not predict that tariff escalation increases welfare. We show that tariff escalation is usually welfare-improving when final-good production occurs under increasing returns to scale. In our vertical model, countries export inputs directly or by embodying them in final goods. The latter raises welfare if final-good efficiency is increasing in sector size, and a disproportionately high final-good tariff exploits this benefit. When tariffs are the only available instruments, this effect dominates input-tariff motives for most parameter values.

Multinational firms (MNEs) dominate trade flows, yet their global production decisions are often ignored in firm-level studies of exporting and importing. Using newly merged data on US firms' trade and multinational activity by country, we show that MNEs are more likely to trade not only with countries in which they have affiliates, but also with other countries within their affiliates' region. We rationalize these patterns with a new source of firm-level scale economies that arises when country-specific fixed costs to source from, or sell in, a market are shared across all the MNE's plants. These shared fixed costs create interdependencies between a firm's production and trade locations that generate third-market responses to bilateral trade policy changes.

We quantify and explain the firm responses and worker impacts of foreign demand shocks to domestic production networks. To capture that firms can be indirectly exposed to such shocks by buying from or selling to domestic firms that import or export, we use Belgian data with information on both domestic firm-to-firm sales and foreign trade transactions. Our estimates of firm responses suggest that Belgian firms pass on a large share of a foreign demand shock to their domestic suppliers, face upward-sloping labor supply curves, and have sizable fixed overhead costs in labor. Motivated and guided by these findings, we develop and estimate an equilibrium model that allows us to study how idiosyncratic and aggregate changes in foreign demand propagate through a small open economy and affect firms and workers. Our results suggest that the way the labor market is typically modeled in existing research on foreign demand shocks—with no fixed costs and perfectly elastic labor supply—would grossly understate the decline in real wages due to an increase in foreign tariffs.

In granular settings in which people choose from a large set of potential residence-workplace pairs, observed outcomes in part reflect idiosyncratic choices. Using both Monte Carlo simulations and event studies of neighborhood employment booms, we demonstrate that calibration procedures that equate observed shares and modeled probabilities perform very poorly in these high-dimensional settings. Parsimonious specifications of spatial linkages deliver better counterfactual predictions. To quantify the uncertainty about counterfactual outcomes induced by the idiosyncratic component of individuals' decisions, we introduce a quantitative spatial model with a finite number of individuals. Applying this model to Amazon's proposed second headquarters in New York City reveals that its predicted consequences for most neighborhoods vary substantially across realizations of the individual idiosyncrasies.