Borders have a sizable negative impact on trade flows. Given the vast number of individual goods potentially traded, this "border effect" could have two possible explanations: (1) less international than domestic trade in the goods that are actually traded between countries ("flow"), or (2)...

Empirical evidence of the impact of borders on international trade flows using the gravity equation approach abounds. This paper examines the empirical relevance of state borders in U.S. interstate trade for various specifications of the gravity equation. We find a large and economically...