The broad objective of this dissertation is to understand the economic implications of globalization, with a particular focus on two key aspects: international migration and trade liberalization. The dissertation is comprised of three chapters. In Chapter 1, my coauthor and I examine the impacts of Japan's immigration policy reforms on labor market outcomes and sectoral production across regions. In Chapters 2 and 3, I analyze the effects of China's trade liberalization, specifically its WTO accession in 2001, with a special emphasis on firms' input trade. Chapter 1 examines the impact of immigrant workers on the regional economies of the host country. We focus on Japan, which has expanded the foreign employment in the total workforce over the last three decades in response to the shrinking domestic workforce. We develop a quantitative spatial model to evaluate the gains of foreign employment, i.e., the consequences of an inflow of foreign workers on aggregate welfare, local wages, employment, and production. Our model features three crucial aspects--occupation, region, and sector--that interact with each other to shape the local labor market and production responses to immigration shocks. We quantify the model using the newly available micro-level data on foreign workers and conduct counterfactual exercises to evaluate the past and future immigration policy reforms. We find that in regions where foreign workers tend to gravitate, there was a substantial negative impact on the wages of low-education domestic workers. At a nationwide level, there is a minimal gain of social welfare. We argue that these results suggest that the Japanese labor market is segmented spatially, particularly for low-education workers. We also highlight the importance of the sectoral dimension in understanding the impact of foreign workers. Specifically, the skewed occupational distribution of foreign workers has pronounced implications on sectors that are intensive in occupations with a larger proportion of foreign workers and sectoral input-output linkage plays a key role in determining the regional impacts. Chapter 2 investigates the decision of firms to import intermediate inputs and their impact on firm performance. Previous research in development economics and international trade has highlighted the benefits of imported inputs for firms, including lower marginal cost of production and positive productivity implications from, e.g., interaction with foreign suppliers. Using Chinese firm-level data from the early 2000s, when trade liberalization occurred, I develop a dynamic structural model of a firm's importing decision that captures both static and dynamic benefits of using imported inputs. I estimate the firm's production function while controlling for unobserved productivity and confirms that the marginal cost of production decreases when using imported inputs (i.e., Ethier's love-of-variety effect), and their use has positive impacts on future productivity. By using the estimated model, I show that subsidizing the fixed cost of importing is more effective in increasing the overall import participation rate than subsidizing the startup sunk cost of importing. Chapter 3 examines the impact of trade liberalization on a firm's intermediate imports and aggregate outcomes, with a focus on heterogeneous impacts across locations within a country. I use Chinese firm-level data covering the period of China's trade reforms following its WTO accession in 2001 and finds that coastal firms, despite their geographic advantage in international trade, are less likely to import, use fewer imports, and spend less on imported inputs than inland firms on average. I also find evidence that coastal firms are less likely to import because domestic inputs are more available than in the inland region. To explain these findings, I develop a spatial general equilibrium model of a firm's input trade, which features multiple regions in a country, endogenous market size, and firm selection. I find that a reduction in international trade costs increases market size and the number of active firms in the coastal region, making the domestic input bundle relatively cheaper. As a result, the model replicates the empirical regularities that coastal firms are less likely to import and use fewer imports than inland firms.