Trading Places, Trading Platforms: The Geography of Trade Policy Realignment

What motivates politicians and political parties to shift their positioning on an issue? Focusing on the case of trade policy in advanced plurality countries, I argue that the relative positioning of parties on an existing issue can change even when the preferences of the key actors (voters and politicians) are held constant, and even when party leaders continue to represent the same constituencies. In advanced plurality countries, college-educated voters support free trade, and high-density constituencies are predominantly represented by Left incumbents. As college-educated workers migrate to high-density constituencies in pursuit of higher wages, Left incumbents increasingly embrace free trade, while Right incumbents take more protectionist positions. I provide empirical support for several observable implications of my theory.