Does the Colonial Trade Premium Still Exist? Sectoral and Temporal Dynamics in the Structural Gravity Model

Colonial trade premiums persist in primary commodities but vanish in high-technology sectors. Whether this divergence reflects a uniform decline modulated by sector characteristics or fundamentally distinct dynamics across product categories remains unresolved. This paper estimates a sectoral PPML structural gravity model using 5.67 million bilateral trade observations spanning 111 countries, 16 WITS sectors, and 29 years (1995–2023). Three results stand out. First, the aggregate colonial premium of 18.6% conceals sectoral coefficients ranging from +101.6% in fuels to −33.7% in transportation equipment. Second, colonial trade in primary sectors grows at 0.25% per year, while colonial trade in high-technology sectors contracts at 0.72% annually—a pattern robust to pair×sector fixed effects that absorb all time-invariant bilateral heterogeneity. Third, a quadratic specification identifies a turning point around 2013, after which the aggregate premium begins to erode. The sectoral decomposition reconciles contradictory findings in the literature by showing that what appears as colonial decline at the aggregate level is a compositional shift from primary-commodity dependence toward diversified, non-colonial sourcing in manufactures and technology.殖民贸易溢价在初级商品领域持续存在，但在高技术部门则消失殆尽。这种差异究竟是由部门特征调节的统一衰减所致，还是不同产品类别间存在本质迥异的动态机制，目前尚无定论。本文采用涵盖111个国家、16个世界一体化贸易解决方案（WITS）部门、时间跨度29年（1995-2023年）的567万组双边贸易观测数据，对部门层面的泊松伪极大似然（PPML）结构引力模型进行了估计。本文得出三项核心结论：其一，18.6%的总体殖民贸易溢价掩盖了部门间的系数差异——燃料部门的溢价系数高达101.6%，而运输设备部门的系数则为-33.7%；其二，初级部门的殖民贸易以年均0.25%的速度增长，而高技术部门的殖民贸易则以年均0.72%的速率收缩，这一模式在控制双边配对-部门固定效应（可吸收所有时不变双边异质性）后依然稳健；其三，二次设定的模型识别出2013年左右的拐点，在此之后总体殖民贸易溢价开始逐步衰减。部门层面的分解研究调和了现有文献中的矛盾结论：总体层面看似出现的殖民贸易衰减，实则是贸易结构的转型——即从依赖初级商品的殖民贸易来源，转向制造业与技术领域多元化、非殖民化的采购渠道。