| 100% | BUG | 3 | Tributary of the Narew River forming part of Poland's border with both Belarus and Ukraine |
| 89% | BUG | 3 | Tributary of the Narew River forming part of Poland's border with Belarus and Ukraine |
| 47% | ODER | 4 | River that forms part of the border between Germany and Poland |
| 47% | KASAI | 5 | Tributary of the Congo River that forms part of the border between the Democratic Republic of the Congo and Angola |
| 43% | IOWA | 4 | The Mississippi and Missouri rivers form parts of its border |
| 43% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
| 43% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |
| 41% | BERMEJO | 7 | River of N Argentina forming part of the border with Bolivia |
| 41% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
| 41% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
| 41% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
| 41% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
| 41% | ELBE | 4 | River that formed part of the border between East and West Germany |
| 41% | SNAKE | 5 | — River, US watercourse forming part of the border between Idaho and Oregon |
| 40% | PERU | 4 | The Putumayo River forms part of its northern border |
| 39% | DOURO | 5 | River that forms part of the border between Spain and Portugal before flowing west to the Atlantic |
| 39% | YALU | 4 | River that forms a large part of the border between North Korea and China |
| 39% | NIAGARA | 7 | River that forms part of the U.S.-Canada border |
| 38% | IOWA | 4 | The Big Sioux River forms part of its border |
| 37% | URAL | 4 | River forming part of the boundary between Europe and Asia |
| 36% | MAMORE | 6 | River rising in the Andes that forms part of the Bolivia-Brazil border |
| 36% | GUADIANA | 8 | River that forms part of the Spain-Portugal border |
| 36% | RHINE | 5 | River that forms part of the France/Germany border |
| 36% | WABASH | 6 | River that forms part of the Illinois-Indiana border |
| 35% | OHIO | 4 | River forming the borders of parts of five states |
| 34% | TAMAR | 5 | River that forms most of the border between Cornwall and Devon |
| 34% | ALABAMABORDER | 13 | The Chattahoochee River forms part of it |
| 34% | PUTUMAYO | 8 | River forming most of the border of Colombia with Peru also known as the Rio Ica |
| 34% | PUTUMAYO | 8 | River also known as the Rio Ica forming most of the border of Colombia with Peru |
| 32% | THROAT | 6 | Part of the body that's with ear and nose in ENT |