學術界在考察開埠之後的貿易演變時，多以一般經濟理論中的貿易對區域經濟所產生的影響作為分析基礎，集中於探討西方影響之下阻礙或推動對外貿易發展的諸多因素及其所產生的影響力。本文主要是基於量化統計，考察貿易演變的區域特質和區域結構諸要素在塑造口岸貿易演變中的重要性。文章認為，除去外來影響之外，天津進出口商品的變化受區域腹地結構變動的影響顯著。從某種意義上講，天津的對外貿易就是華北等廣大內地的對外貿易，沒有華北等廣大內地的繁榮，天津的貿易是不會繁榮的。口岸貿易本身作為一種外向型經濟，對外經濟關係無疑是晚清以降口岸貿易發展的重要契機和推動力，但是，應該說，這並非唯一因素，在許多情況，兩者的關係常常表現為間接而不是直接，在某種情況下，也許並非是最為重要因素。我們在追究外力因素的同時，有必要重視其本身的發展邏輯。

This article reviews the important role of regional components and structure in molding the development pattern of port trade through statistical analysis. While most other studies on this topic have chiefly focused on how trade impacts regional economics and how influences from the western world have impeded or enhanced foreign trade. Excluding external factors, the changes in the import and export of goods is remarkably influenced by regional structural changes across the hinterland. To some extent, the external trade pattern of Tianjin is also the external trade pattern of its hinterland, northern China (known as Hwa-Bei or ＂North China＂). In the late Ching Dynasty the prosperity of Tianjin's external trade was based on the prosperity of Hwa-Bei's economy. Port-trade, a kind of external economy, was one of the most important trade incentives and prospects. But port-trade was not the only reason for the city's prosperity. The relationship between port trade and regional society, though indirect in certain circumstances, was also a contributing factor. This examination uses a specific reciprocal logic of development to explore the external causes.