This paper studies how the first wave of globalization shaped electoral populism in the United States. We assemble a new county-level dataset covering presidential, congressional, and gubernatorial elections between 1870 and 1900 and ask whether deeper integration into international trade increased support for populist parties. We measure globalization exposure with a new port market access index that captures counties’ connectivity to major US ports, weighted by port-level international trade volumes and adjusted for transportation costs. Counties with greater port market access consistently exhibit higher populist vote shares. We then examine the economic mechanisms underlying this relationship. Using a county-level crop portfolio price index constructed from fixed within-county value shares, we show that greater port market access is associated with larger declines in agricultural prices. The political effects of globalization are significantly stronger in counties initially specialized in crops that experienced the largest global price declines. These results highlight the historical origins of the globalization–populism link and suggest that economic dislocation has long been a catalyst for political backlash.