E pluribus unum? Political fractionalization and deviations from the law of one price in the USA
研究发现美国城市间的政治差异对一价定律偏离的影响与距离相当，两城市若同为民主党或共和党占优则偏离更小，表明政治分歧构成显著的竞争壁垒。
Abstract The magnitude of deviations from the Law of One Price (LOP) across cities depends on a number of characteristics, including language differences, distance, and other correlates of trade costs. We show that in the USA, political differences between cities are an equally important determinant of LOP deviations. LOP deviations are smaller if the cities are both strongly Democrat or both strongly Republican. These effects are of a similar order of magnitude to those of distance, and suggest that political differences represent a substantial barrier to competition.