Income Inequality and Ideological Positions in the US Congress

Over the past twenty years, there has been much discussion about two of the most important recent trends in American politics: the increase in income inequality in the United States and the increase in ideological and partisan polarization, particularly in the U.S. House. These two national-level trends are commonly thought to be positively related. But, there are few tested theoretical connections between them, and it is potentially problematic to infer individual-level behavior from these aggregate-level trends. In fact, an examination of the literature reveals, at least, three different theoretical outcomes for district-level income inequality on voter and congressional ideological positions. I explore these district-level theoretical and empirical possibilities as well as test them over decades with three different measures of income inequality. I argue and demonstrate that higher district levels of income inequality are related to higher levels of ideological liberalism in the U.S. House. This stands in contrast to the national-level trends, but it tracks closely to traditional understandings of congressional behavior.