Mason–Dixon line, 1767
39°43′N
A colonial land dispute drew this line; slavery later made it a symbol of North and South.
Mason and Dixon surveyed the Pennsylvania–Maryland boundary in 1763–1767. As Pennsylvania moved toward ending slavery, the line gained its lasting association with the divide between free and slave states.
- exact 39°43′20″N
- the surveyed line steps around obstacles; the parallel does not
Read about Mason–Dixon line, 1767
United States lines
- Adams–Onís line, 1819 · 42°00′N
- Missouri Compromise line, 1820 · 36°30′N
- Pinckney's Treaty line, 1795 · 31°00′N
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