| 100% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
| 100% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
| 77% | ODER | 4 | River that forms part of the border between Germany and Poland |
| 77% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
| 77% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
| 77% | ELBE | 4 | River that formed part of the border between East and West Germany |
| 75% | DOURO | 5 | River that forms part of the border between Spain and Portugal before flowing west to the Atlantic |
| 68% | KASAI | 5 | Tributary of the Congo River that forms part of the border between the Democratic Republic of the Congo and Angola |
| 67% | TAMAR | 5 | River that forms most of the border between Cornwall and Devon |
| 66% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
| 66% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |
| 65% | YALU | 4 | River that forms a large part of the border between North Korea and China |
| 61% | SNAKE | 5 | — River, US watercourse forming part of the border between Idaho and Oregon |
| 60% | GUADIANA | 8 | River that forms part of the Spain-Portugal border |
| 60% | RHINE | 5 | River that forms part of the France/Germany border |
| 60% | WABASH | 6 | River that forms part of the Illinois-Indiana border |
| 59% | NIAGARA | 7 | River that forms part of the U.S.-Canada border |
| 56% | URAL | 4 | River forming part of the boundary between Europe and Asia |
| 52% | DEE | 3 | River that forms part of the England/Wales boundary |
| 51% | MORAVA | 6 | River that forms the border between Slovakia and Austria |
| 51% | MEKONG | 6 | River that forms the border between Laos and Myanmar |
| 51% | MAMORE | 6 | River rising in the Andes that forms part of the Bolivia-Brazil border |
| 49% | IOWA | 4 | The Mississippi and Missouri rivers form parts of its border |
| 49% | MEKONG | 6 | River that forms much of the Laos/Thailand border |
| 48% | ORINOCO | 7 | Part of the Venezuela/ Colombia border |
| 47% | AMUR | 4 | River that forms the boundary between Manchuria and Russia |
| 46% | TWRCH | 5 | River that formed the ancient boundary between Brecknockshire and Carmarthenshire |
| 46% | DRINA | 5 | River that forms the boundary between Bosnia and Herzegovina and Montenegro |
| 45% | BUG | 3 | Tributary of the Narew River forming part of Poland's border with Belarus and Ukraine |
| 45% | BERMEJO | 7 | River of N Argentina forming part of the border with Bolivia |