Tianjin is located on Bohai Gulf, approximately 75 miles (120 kilometers) from Beijing. It was the imperial port of China, by virtue of that proximity. Tianjin also served as one of the most important "treaty ports" occupied and/or controlled by western nations and Japan for various years before 1950.
Tianjin is pivotally located along the East coast corridor between "Dongbei" – the northeast (the provinces of Heilongjiang, Jilin and Liaoning, which are also referred to as Manchuria) and Jinan, Nanjing, Shanghai and points south. Both the most direct expressway route (interstate standard) and high speed rail line from Shanghai to Dongbei cross through Tianjin rather than larger Beijing.
Image: http://www.newgeography.com
