National Borders, Trade and Migration


John Helliwell


The paper confirms a strikingly large effect of national borders on trade patterns. Estimates comparing trade among Canadian provinces with that between Canadian provinces and US states show interprovincial trade in 1988–90 to have been more than 20 times as dense as that between provinces and states, with some evidence of a downward trend since, owing to the post-FTA growth in trade between Canada and the USA. Using approximate data for the volumes and distances of internal trade in OECD countries, the 1988–92 border effect for unrelated OECD countries is estimated to exceed 12. Estimates from a census-based gravity model of interprovincial and international migration show a much higher border effect for migration than for trade, with interprovincial migration among the Anglophone provinces almost 100 times as dense as that from US states to Canadian provinces.