What is the longest river entirely within one country?

The Yangtze is the longest river entirely within one country. It runs for roughly 6,300 kilometres through China, from the Tibetan Plateau to its outlet in the East China Sea near Shanghai.

Known in Chinese as the Chang Jiang, the river flows generally eastward through some of China’s most important landscapes and cities. Its basin includes fertile agricultural regions, major industrial centres, and the Three Gorges, where the Three Gorges Dam was built. The Yangtze is also central to Chinese history, transport, and food production.

The wording matters because many of the world’s longest rivers cross national borders. The Nile and Amazon are longer overall, but neither lies entirely within one country. China also has the Yellow River, another historically important river that remains wholly within Chinese territory, though it is substantially shorter.

The river’s exact length varies slightly by source because its upper headwaters are difficult to define. Most modern references place the main river system at about 6,300 kilometres, with its headwaters in the Tanggula Mountains of Qinghai Province.