We present a model of multinational firms that predicts that aggregated affiliates' sales fall in distance. The distance effect on foreign affiliate sales is driven by the extensive margin: distance affects the number of affiliates negatively while it has an ambiguous effect on the average...

In a recent meta study, Disdier and Head (2008) summarize 103 empirical studies that find that the (absolute value of the) distance coefficient in a gravity estimation of bilateral exports does not fall over time. Including zero-trade flows is suggested as a solution to this "distance-puzzle"...