A transboundary river is a river that crosses at least one political border, either a border within a state or an international boundary. Bangladesh has the highest number of these rivers, with at least 58 major rivers that enter the country from the Republic of India, including two of the world's largest rivers, the Brahmaputra and the Ganges. The Naf River is the only river that flows via Bangladesh into Myanmar.
The hydrologic and political effects of rivers that cross significant boundaries are enormous. Rivers have positive effects in that they carry a significant amount of sediment, which aids in building land in estuarine regions. However, this sediment raises the height of riverbeds, thereby causing flooding. International conventions governing water sharing have led to complex political disputes.[1]
| River | Length (km) | Countries | |
|---|---|---|---|
| Amazon | 6,500 |  Brazil Colombia Peru | |
| Brahmaputra | 3,848 |  Bangladesh China India | |
| Colorado | 2,333 |  Mexico United States | |
| Columbia | 2,000 |  Canada United States | |
| Danube | 2,860 |  Austria Bulgaria Croatia Germany Hungary Romania Serbia Slovakia Ukraine | |
| Daugava | 1,020 |  Belarus Latvia | |
| Dnieper | 2,200 | Belarus Ukraine | |
| Euphrates | 2,800 |  Iraq Turkey | |
| Ganges | 3,084 | Bangladesh India | |
| Ichamati | 334 | Bangladesh India | |
| Indus | 3,500 | China India Pakistan | |
| Irrawaddy | 2,210 | China Myanmar | |
| Mekong | 4,350 |  Cambodia China Myanmar Thailand | |
| Meuse | 925 |  Belgium France Netherlands | |
| Niger | 4,180 |  Benin Guinea Mali Niger Nigeria | |
| Nile | 6,853 |  Burundi Egypt Eritrea Ethiopia Kenya Rwanda Sudan Uganda | |
| Rhine | 1,230 | Austria France Germany Liechtenstein Netherlands Switzerland | |
| Rhône | 813 | France Switzerland | |
| Rio Grande | 3,051 | Mexico United States | |
| Tagus | 1,007 |  Portugal Spain | |
| Tigris | 1,850 | Iraq Turkey | |
| Yukon | 3,190 | Canada United States | |
| Zambezi | 2,474 |  Angola Botswana Mozambique Namibia Zambia Zimbabwe |