Obvious bases by which to compare the world’s great rivers include the size of the drainage area, the length of the main stem, and the mean discharge. However, reliable comparative data, even for the world’s greatest rivers, is often difficult to obtain. It is possible that well over 100 of the greatest rivers may exceed a 1,600-kilometre length on their main stems. Measuring from the headwaters of the most distant source, the five longest rivers in the world are the Nile, the Amazon–Ucayali–Apurímac, the Yangtze, the Mississippi–Missouri–Red Rock, and the Yenisey–Baikal–Selenga. Area-length-discharge combinations vary considerably, although length tends to increase ...(100 of 32811 words)