本文以產業組織的觀點出發，藉由本國與外國廠商間之互動及貿易政策來解釋一國產業之貿易開放程度，並以美國在1977年到1990年間十九大製造業作實證分析，實證結果顯示：當外國市場規模（相對於美國市場規模）擴大，美國成本競爭力（或生產力）提高，廠商間勾結程度增加，產品差異化程度加深與美金升值時，美國貿易之開放程度顯著地提高；而提高運輸成本對美國貿易之開放程度有顯著性之負面影響；最後，關稅、非關稅、廠商家數與工會力量對美國貿易之開放程度有反面之影響，但效果不顯著。

　　　　　This paper develops and tests a simple oligopoly model for the determinants of trade openness across industries in U.S. manufacturing between 1977 and 1990. We find that as the market size in the rest of the would relative to that in the U.S. increases, U.S. labor productivity rises, the degree of collusion among firms becomes higher, product differentiation becomes larger, and the U.S. dollar appreciates, U.S. manufacturing industries significantly become more open. However, transportation costs significantly discourage the trade openness of U.S. manufacturing industries. Finally, tariffs, nontariff barriers, the number of firms and the power of labor unions seem to have negative but insignificant effects on the trade openness of U.S. manufacturing industries.