本文綜合過去的研究成果和新史料，嘗試從貿易型態的角度，將十九世紀中葉臺灣的港口城市分成小口型和正口型兩種傳統港市，以及開港後的國際港市。這些港口城市基於政策、港口規模及貿易網絡的變化，彼此之間產生市場圈互相從屬，卻又直接對外貿易的狀態，而形成地域間既從屬又分立的雙重貿易結構。不同類型港口城市的貿易型態也有所差別。傳統港市主要從事中式帆船貿易，核心貿易圈集中於福建地區，且由於貿易規模較小，大多採交互計算或是現金交易來解決財務關係，郊也始終在這些傳統港市中扮演重要角色。正口型港市因貿易規模較小口型大，因此與對岸固定商號之間發展出委託貿易制度，雙方合夥投資關係亦相當密切。小口型港市則以由出海負責的整船貿易為主，商業投資侷限於臺灣本地。1860 年臺灣開港之後，臺灣南北兩個正口港及其附口升格為國際港埠，並以鹿港為界將全臺瓜分為兩大市場圈。國際商品的茶、糖、樟腦大多集中到此再對外輸出。洋行、媽振館帶來西方資本、技術、新金融制度及商業文化。輪船運輸不但逐漸取代帆船，貿易網絡也擴大到全世界。由於貿易規模大幅擴張，需要巨額資金流通，臺北首先出現中國內地流行已久的錢莊與匯單館。另一方面，部分臺灣商人透過地緣優勢逐漸參與國際商品的生產與輸出，迅速累積財富，不但可以與洋行相抗衡，甚至直接涉足國際貿易，設立仿西式的貿易公司。十九世紀中後葉臺灣商人的異軍突起，則反映了臺灣本土經濟力的成長。

With reference to past research and new sources, this paper attempts to classify the ports of mid-19th-century Taiwan into a three-level hierarchy, namely match official ports and minor ports, which are traditional ones, and treaty ports opened for international trade exchange after 1860. In terms of government policy, size and changes in trade network, these ports had mutually subordinate market spheres and yet they are independent in external trade with foreign countries, thus creating a dual trade system between regions. Owing to their difference in geography, accessibility, market size and trade volume, the commodities traded, merchant organizations, trade network and system in these economic spheres varied widely. Towards the end of the 19th century, traditional ports continued to maintain direct trade with coastal cities of China, concentrating mainly in Fujian district. Hence, they had all along been dependent on the China market and were not much exposed to the western impact. At match official ports, cross-strait merchants and firms operated under the cooperative commissioning system and maintained close business ties with mutual investments. On the contrary, commercial investments at minor ports were restricted to local businesses and trade exchange was mainly handled by supercargo responsible for the sale and purchase of merchandize transported by junks. The opening of treaty ports certainly marked a turning point in Taiwan’s trade development. With Lugang as the demarcation, the island was divided into two market spheres, one in the north and one in the south, each with two international ports handling external global trade. There existed wide differences in trade operations between traditional ports and international treaty ports. Traditional ports served as subsidiaries to treaty ports and imported international merchandise and foreign goods through them. With traditional junks replaced by steamers as the main means of transportation, international merchandise including tea, sugar and camphor were gathered at treaty ports for exports to other countries in the East and West. Western companies and financial institutions sprang up bringing in new technologies and novel capital flow mechanisms. The former trade network also expanded from the Fujian hub to the entire world, ushering Taiwan into the global economic system. Increase in international trade volume implied huge flow of money and capital, and traditional approaches to settling payments by cash or offsetting were no longer practicable and fell short of meeting the needs for global business exchange. Native banks and remittance banks, long popular in China proper, first appeared in Taipei. It is worthy to note that Taiwanese merchants with local competitive advantages gradually gained control over the production and export of international merchandise. Their rapid accumulation of wealth put them on equal par with western companies, enabling them to be engaged directly in international trade. They set up western-style companies and ran their business with western corporate management practices. The rise of these local merchants with power and influence surpassing that of Chinese and foreign ones reflected the growth of Taiwan’s own economic strength.