Which river is traditionally ranked first on Wikipedia’s list of river systems by length? The answer is the Nile.
The Nile is traditionally ranked as the world’s longest river system, with the Nile–White Nile–Kagera system commonly listed at about 6,650 km. It flows north through northeastern Africa and empties into the Mediterranean Sea. Its basin connects a large part of eastern Africa, including countries around the Great Lakes and the upper Nile.
The river is formed principally by the White Nile and Blue Nile, which meet at Khartoum in Sudan. The Blue Nile rises in Ethiopia and supplies much of the system’s seasonal floodwater, while the White Nile provides a steadier flow. Ancient Egyptian civilization developed along the lower Nile, where its floodplain supported agriculture in an otherwise arid landscape.
The ranking is not completely settled. Measurements of the Amazon vary depending on which headwater and mouth channels are counted, and some studies place it first. Wikipedia’s wording preserves the conventional Nile ranking while acknowledging that river-length comparisons depend on definitions and measurement methods.