The Port of Tianjin (Tianjin Gang, ), formerly known as the Port of Tanggu, is the largest port in Northern China and the main maritime gateway to Beijing. The name "Tianjin Xingang"(), which strictly speaking refers only to the main seaport area, is sometimes used to refer to the whole port. The Port is located on the western shore of the Bohai Bay, centered on the estuary of the Haihe River, 170 km south east of Beijing and 60 km east of Tianjin city. It is the largest man-made port in mainland China, and one of the largest in the world. It covers 121 square kilometers of land surface, with over 31.9 km of quay shoreline and 151 production berths at the end of 2010.
Haihe river ports
The lower course and estuary of the Haihe is the main stem of a large navigable basin, as well as the westernmost seashore of the North China Plain, making it an obvious location for a major navigational hub. The history of the Haihe ports follows this dual nature of being a hub of both inland and marine waterways, with routes changing according to political and natural changes.
First records of port activity in the Haihe date from the late Eastern Han dynasty, when Cao Cao built two canals connecting the Haihe to support his campaigns against the Wuhuan. It was, however, only after the completion of the first Grand Canal by Emperor Yang of the Sui dynasty that the lower Haihe gained importance as a logistics hub, transporting southern grain to the army outposts of northeast China. The same military necessity caused the Tang to establish the Sanhui Harbor () as both a fluvial hub and a seaport at the confluence of the Yongji Canal (永濟渠), the Hutuo River (滹沱河) and the Luhe River (潞河), on modern day Junliangcheng (), a fact still preserved in the town's name. Sanhui Harbor served as a forward logistics base for the Tang's campaigns against the Khitans and Goguryeo, with coastal ships and canal barges transporting 500,000 dan of grain each year.
In 960, the Haihe became the border between the Song dynasty and the Liao dynasty. The Haihe port became divided: the Song port was Nigu Harbor (泥沽海口) to the south of the Haihe, and the Liao port was at Junliangcheng, to the north. In 1043, the Yellow River had one of its frequent cataclysmic course changes, and until 1194 it took over the course of the Haihe. In that 150 years span, the enormous runoff of silt from the "Flowing Mud" caused a major change in the coastline: from its original position at Junliangcheng, the shoreline moved forward around 23 km to the present day line of Tanggu, Beitang and Gaoshaling. This led to the decline of Junliangcheng, and a new main port was established further upriver at Zhigu (直沽, now Tianjin city).
In 1153, the Jin dynasty moved its capital to Zhongdu (now Beijing). The massive needs of the capital city made Zhigu a critical grain hub, moving up to 1.7 million dan of grain per year. The Mongol conquest made this trade even more necessary when, in 1264, the Yuan dynasty established its capital at Dadu, also on the site of modern Beijing.
Feeding the enormous needs of Dadu was the spur for the creation of regular seagoing routes to complement the inland waterways, which (despite much expansion) were reaching their limit capacity. Sea routes connecting Liujiagang in Zhejiang province and Zhigu's Yangcun (杨村) wharf were established in 1276 (the Tang coast-hugging route, taking 120 days to complete), and in 1282 (a route taking 30 days to complete). A breakthrough occurred in 1293, when a third sea route was opened that took a more direct open-sea path from Liujiagang to Yangcun, going eastwards from the Yangtze mouth into the “Black Water Ocean” (the deepest section of the Yellow Sea), turning at the tip of the Shandong peninsula around Chengshan Cape, entering the Bohai Sea through the Miaodao Strait, and then going directly from Laizhou into the Haihe mouth. This route required more complex navigation, but it took less than ten days to sail, and it is in essence the route still used today for shipping between Shanghai and Tianjin. To assist this burgeoning sea trade, in 1318 the first recorded aid to navigation in the region was established in the Longwangmiao temple at the Haihe mouth. During daytime, white cloth flags were raised on high poles. At night, lamps were lit and raised to guide approaching boats.