The Political Determinants of International Trade: The Major Powers, 1907–1990

We test three arguments about the effect of international politics on trade flows. The first argument states that trade flows are greater between states with similar interests than those with dissimilar interests, the second that trade flows are greater in democratic dyads than nondemocratic dyads, and the third that trade flows are greater between allies. We examine trade flows between the major powers from 1907 to 1990. This period provides variation on all three independent variables of interest and allows us to separate the three arguments empirically. We estimate a gravity model of trade with the above political variables added. Our results demonstrate that joint democracy and common interests increase trade in a dyad, but alliances generally do not, even when controlling for polarity of the system.