100% | IOWA | 4 | The Big Sioux River forms part of its border |
69% | PERU | 4 | The Putumayo River forms part of its northern border |
66% | IOWA | 4 | The Mississippi and Missouri rivers form parts of its border |
59% | ARG | 3 | The Iguazu Riv. forms part of its border |
59% | ALABAMABORDER | 13 | The Chattahoochee River forms part of it |
58% | ARAS | 4 | River forming part of the border between Azerbaijan and Iran |
58% | MOSELLE | 7 | River forming part of the border between Germany and Luxembourg |
56% | RHINE | 5 | River that forms part of the France/Germany border |
55% | ODER | 4 | It forms part of the Polish/German border |
55% | GUADIANA | 8 | River that forms part of the Spain-Portugal border |
55% | WABASH | 6 | River that forms part of the Illinois-Indiana border |
54% | OHIO | 4 | River forming the borders of parts of five states |
53% | NIAGARA | 7 | River that forms part of the U.S.-Canada border |
52% | ODER | 4 | River that forms part of the border between Germany and Poland |
52% | ORINOCO | 7 | River that forms part of the border between Colombia and Venezuela |
52% | MOSELLE | 7 | River that forms part of the border between Germany and Luxembourg |
52% | DOURO | 5 | River that forms part of the border between Spain and Portugal |
52% | RIONEGRO | 8 | River that forms part of the border between Colombia and Venezuela |
52% | ZIMBABWE | 8 | Victoria Falls forms part of its border |
52% | ELBE | 4 | River that formed part of the border between East and West Germany |
51% | EMS | 3 | River forming part of the Germany-Netherlands boundary |
50% | BERMEJO | 7 | River of N Argentina forming part of the border with Bolivia |
50% | URAL | 4 | River forming part of the boundary between Europe and Asia |
49% | DOURO | 5 | River that forms part of the border between Spain and Portugal before flowing west to the Atlantic |
49% | BUG | 3 | Tributary of the Narew River forming part of Poland's border with Belarus and Ukraine |
49% | ENDPAPER | 8 | Part of it forms the flyleaf |
49% | BUG | 3 | Tributary of the Narew River forming part of Poland's border with both Belarus and Ukraine |
48% | SNAKE | 5 | — River, US watercourse forming part of the border between Idaho and Oregon |
47% | MAMORE | 6 | River rising in the Andes that forms part of the Bolivia-Brazil border |
46% | ODER | 4 | It forms part of Germany's eastern border |