What is the longest river in the world?
The Nile River, at approximately 6,650 km (4,130 miles), is traditionally recognized as the longest river in the world, though some scientific studies argue the Amazon River may rival or exceed it depending on how its source is measured.
The two contenders
Why the Nile is considered the longest
The Nile flows northward through northeastern Africa, originating from the lakes and highlands of Central Africa (with the White Nile's farthest source in Burundi or Rwanda) and the Ethiopian highlands (Blue Nile). It passes through Uganda, Sudan, and Egypt before emptying into the Mediterranean Sea. Its total length of ~6,650 km has been the standard geographical consensus for over a century.
The Amazon, flowing through South America primarily across Brazil, drains the largest river basin on Earth and carries by far the greatest volume of water — roughly 20% of all freshwater discharged into the world's oceans. Its length measurement is disputed because its most remote headwater source in the Peruvian Andes (the Mantaro River tributary) was only identified in studies from 2007 and 2014, pushing some estimates above the Nile's figure.
Most authoritative sources — including the Encyclopædia Britannica, National Geographic, and the United Nations — continue to list the Nile as the longest river, while acknowledging the measurement debate.
World's longest rivers compared
| Rank | River | Length (km) | Continent | Empties into |
|---|---|---|---|---|
| 1 | Nile | 6,650 | Africa | Mediterranean Sea |
| 2 | Amazon | ~6,400–6,992 | South America | Atlantic Ocean |
| 3 | Yangtze | 6,300 | Asia | East China Sea |
| 4 | Mississippi–Missouri | 6,275 | North America | Gulf of Mexico |
| 5 | Yenisei–Angara | 5,539 | Asia | Kara Sea (Arctic) |
Key moments in the Nile vs. Amazon debate
- 1858Nile source expeditionJohn Hanning Speke identifies Lake Victoria as the source of the White Nile, anchoring the Nile's length calculation.
- 1971Amazon re-measurementBrazilian and Peruvian surveys extend the Amazon's measured length by tracing new headwaters in Peru, narrowing the gap with the Nile.
- 2007Brazilian study challenges consensusA team of Brazilian researchers, using GPS and satellite data, claims the Amazon is longer at ~6,992 km by tracing the Apurímac/Mantaro headwater.
- 2008Scientific debate intensifiesThe claim is contested; methodological differences (where a river 'starts') mean no single figure gains universal acceptance.
- 2014New Peruvian source identifiedFurther field research points to the Cordillera Rumi Cruz glacier as the Amazon's most distant source, keeping the length question open.