The standard gravity model predicts that trade flows increase in proportion to importer and exporter total income, regardless of how income is divided into income per capita and population. Bilateral trade data, however, show that trade grows strongly with income per capita and is largely unresponsive to population. I develop a general equilibrium Ricardian model of trade that allows the elasticity of trade with respect to income per capita and with respect to population to diverge. Goods are of various types, which differ in their income elasticity of demand and in the extent to which there is heterogeneity in their production technologies. I estimate the model using bilateral trade data of 162 countries and compare it to a special case that delivers the gravity equation. The general model improves the restricted model's predictions regarding variations in trade due to size and income. I experiment with counterfactuals. A positive technology shock in China makes poor and rich countries better off and middle-income countries worse off.

Welfare depends on the quantity, quality, and range of goods consumed. We use trade data, which report the quantities and prices of the individual goods that countries exchange, to learn about how the gains from trade and growth break down into these different margins. Our general equilibrium model, in which both quality and quantity contribute to consumption and to production, captures (i) how prices increase with importer and exporter per capita income, (ii) how the range of goods traded rises with importer and exporter size, and (iii) how products traveling longer distances have higher prices. Our framework can deliver a standard gravity formulation for total trade flows and for the gains from trade. We find that growth in the extensive margin contributes to about half of overall gains. Quality plays a larger role in the welfare gains from international trade than from economic growth due to selection.

A quantitative model brings together theories linking international trade to quality, technology, and demand for skills. Standard effects of trade on importers and exporters are magnified through domestic input linkages. We estimate the model with data from Colombian manufacturing firms before the 1991 trade liberalization. A counterfactual trade liberalization is broadly consistent with post-liberalization data. It increases skill intensity from 12 to 16 percent, while decreasing sales. Imported inputs, estimated to be of higher quality, and domestic input linkages are quantitatively important. Economies of scale, export expansion, and reallocation of production are small and cannot explain post-liberalization data.

Relative to backward firms, technologically-advanced firms source inputs from other advanced firms. These sourcing patterns lead to a magnification effect of technology adoption. A firm that adopts higher-technology increases the relative supply and demand for higher-technology inputs. As a result, it positively influences the technology of other firms in its production chain. Using data from a Colombian manufacturing survey, we provide evidence that advanced firms disproportionately value advanced inputs. More novel, we provide suggestive evidence that technological advancements in some firms increase the technology of other firms indirectly linked to them through a common input market.

We document strong skill matching in Turkish firms’ production networks. Additionally, in the data, export demand shocks from rich countries increase firms’ skill intensity and their trade with skill-intensive domestic partners. We explain these patterns using a quantitative model with heterogeneous firms, quality choices, and endogenous networks. A counterfactual economy-wide export demand shock of 5% leads both exporters and nonexporters to upgrade quality, raising the average wage by 1.2%. This effect is nine times the effect in a scenario without interconnected quality choices. We use the model to study the conditions for the success of export promotion policies.