Adams–Onís line, 1819
42°00′N
The 1819 northern limit of Spanish North America; now the top of California, Nevada, and Utah.
In 1819, the US and Spain set part of their western boundary at 42°N. Follow its legacy along the northern edges of California, Nevada, and Utah; far east, this latitude also marks much of the New York–Pennsylvania border.
- Adams–Onís Treaty, 1819
- still legible as straight state lines from the Pacific to the Delaware
Read about Adams–Onís line, 1819
United States lines
- Mason–Dixon line, 1767 · 39°43′N
- Missouri Compromise line, 1820 · 36°30′N
- Pinckney's Treaty line, 1795 · 31°00′N
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