When do local economic conditions dominate the politics of globalization? Despite growing interest in region-level analyses, little theoretical or empirical work explores the conditions under which the local economy matters. I integrate regions and migration between regions--i.e., geographic mobility--into the traditional factor-based model of trade politics. This economic geography model reveals that regional trade exposure, in contrast to occupational or industry exposure, will most predict trade positions and voting where significant barriers to geographic mobility exist. To measure regional exposure, I exploit plausibly exogenous variation in Mexican net import competition that followed the implementation of NAFTA. To evaluate heterogeneous effects by geographic mobility, I use a battery of novel and conventional measures: geo-located length of residency, machine learning predictions of migration status, changes in region population, and domestic inflows and outflows from US Commuter Zones. An analysis of county vote shares for two anti-trade populists--Ross Perot (1992-96) and Donald Trump (2016)--shows that local NAFTA exposure increased vote shares for these candidates by an average 1.7 and 1.4 percentage points, respectively. However, both results were highly conditional on geographic mobility. Perot's NAFTA-boost was strongest among those with observable barriers to migration. Trump's NAFTA-boost only materialized in 2016 in regions with limited emigration rates. In contrast, no electoral trade backlash occurred where communities recovered by shedding excess workers. The theory explains 13.6 and 20.1 percent of the variation in these candidates' vote shares. An analysis of public opinion data from a 1992-96 panel shows that these patterns are consistent with NAFTA's effects on private welfare and trade policy preferences. In the European context, an analysis of the China trade shock and regional election data from twenty-eight countries over twenty-six years reveals a high degree of external validity for the theory. Given declining mobility rates, the results from this dissertation suggest a growing political importance of the local economy in globalization politics.