| 100% | HURON | 5 | Lake which forms part of Michigan's northern border |
| 57% | DEADSEA | 7 | Salty lake that forms part of Jordan's border |
| 53% | PERU | 4 | The Putumayo River forms part of its northern border |
| 51% | EURASIAN | 8 | Like the Ural Mountains, which form part of the border between two continents |
| 45% | NIAGARA | 7 | River that forms part of the U.S.-Canada border |
| 44% | ODER | 4 | It forms part of Germany's eastern border |
| 44% | ELBE | 4 | It formed part of East Germany's border |
| 43% | IOWA | 4 | The Big Sioux River forms part of its border |
| 43% | ARG | 3 | The Iguazu Riv. forms part of its border |
| 42% | ZIMBABWE | 8 | Victoria Falls forms part of its border |
| 40% | ALA | 3 | State where the Chattahoochee R. forms part of the border |
| 40% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
| 40% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |
| 40% | IOWA | 4 | The Mississippi and Missouri rivers form parts of its border |
| 40% | ODER | 4 | River that forms part of the border between Germany and Poland |
| 40% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
| 40% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
| 40% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
| 40% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
| 40% | GUADIANA | 8 | River that forms part of the Spain-Portugal border |
| 40% | WABASH | 6 | River that forms part of the Illinois-Indiana border |
| 39% | ISLEROYALE | 10 | Island in NW Lake Superior, Michigan forming part of a US National Park |
| 39% | SNAKE | 5 | — River, US watercourse forming part of the border between Idaho and Oregon |
| 39% | ELBE | 4 | River that formed part of the border between East and West Germany |
| 39% | ISLEROYALE | 10 | Island in northwest Lake Superior, Michigan, forming part of a US National Park |
| 39% | ISLEROYALE | 10 | Island in NW Lake Superior, Michigan, forming part of a US National Park |
| 38% | RHINE | 5 | River that forms part of the France/Germany border |
| 38% | ERA | 3 | Short form of bill S.1774 which, in part, would require secret ballot elections to determine union representation |
| 38% | ODER | 4 | It forms part of the Polish/German border |
| 37% | DEADSEA | 7 | Part of Jordan's border |