HOW MUCH DOES GEOGRAPHY DEFLECT SERVICES TRADE? CANADIAN ANSWERS
利用加拿大各省1997-2007年的高质量双边贸易数据，估计了九类服务贸易的地理壁垒，发现地理因素对服务贸易的阻碍是货物贸易的七倍，且边界效应显著。
We estimate geographic barriers to trade in nine service categories for Canada's provinces from 1997 to 2007 with novel high‐quality bilateral provincial trade data. The border directly reduces average provincial trade with the United States relative to interprovincial trade to 2.4% of its borderless level. Incorporating multilateral resistance reduces foreign trade relative to interprovincial to 0.1% of its frictionless potential. Geography reduces services trade some seven times more than goods trade overall. Surprisingly, intraprovincial (local) trade in services and goods is equally deflected upward, implying that the border increases interprovincial trade much more in services than goods.