International borders / Boundary lines
| Borders/Boundary Lines | Between two Countries |
| Durand Line | Afghanistan & Pakistan |
| Hindenburg Line | Germany & Poland. |
| Mason-dixon Line | Line of demarcation between four states in the United States. |
| Mannerheim Line | Russia-Finland border. |
| Macmahon Line | India & China |
| Medicine Line | Canada & the United States |
| Order-neisse Line | Poland & Germany |
| Radcliffe Line | India & Pakistan. |
| Siegfried Line | Germany on its border with France. |
| 17th Parallel | North Vietnam & South Vietnam |
| 26th Parallel south | Africa, Australia & South America |
| 30th PARALLEL | Equator & the North Pole |
| 38th Parallel | Separates North Korea & South Korea. |
| 42nd Parallel north | New York – Pennsylania Border. |
| 49th Parallel | USA & Canada |