Important Boundary Lines :
- 17th Parallel : between North Vietnam and South Vietnam
- 24th Parallel : between Pakistan and India (not recognized by India)
- 26th Parallel south : between Africa, Australia and South America
- 30th Parallel north : between the equator and the North Pole
- 33rd Parallel north : between United States, parts of North Africa, parts of the Middle East, and China
- 35th Parallel north : between Africa, the Mediterranean Sea, Asia, the Pacific Ocean, North America and the Atlantic Ocean.
- 36th Parallel : between Missouri and the State of Arkansas
- 37th Parallel : between southern boundary of the historic and extralegal Territory of Jefferson
- 38th Parallel : between North Korea and South Korea
- 39th Parallel north : between Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean.
- 40th Parallel north : original northern boundary of the British Colony of Maryland.
- 41st Parallel north : between the State of Colorado with Nebraska and Wyoming and the southern boundary of the State of Wyoming with Colorado and Utah.
- 42nd Parallel north : between New York - Pennsylvania
- 43rd Parallel north : between the State of Nebraska and the State of South Dakota and also formed the northern border of the historic and extralegal Territory of Jefferson.
- 45th Parallel north : between the Equator and the North Pole
- 49th Parallel : between USA and Canada
- Durand Line : between Pakistan and Afghanistan
- Hindenburg Line : between Germany and Poland
- Macmahon Line : between India and China
- Marginal Line : between Russia-Finland
- Mason-Dixon Line : between four states in the United State
- Medicine Line : between Canada and the United States
- Order-Neisse Line : between Poland and Germany
- Radcliffe Line : between India and Pakistan
- Siegfried Line : between Germany and France