[Talk-us] How are US county boundaries legally defined?

[Kevin Kenny]

I hope for your sake that county lines in Missouri are better defined
than they are in upstate New York. There are some county lines in the
Adirondacks that are still shown as 'indefinite' on the state maps
because they've never been formally surveyed and monumented. In the
places where the land is all State Forest and timber tracts belonging
to Finch-Pruyn and International Paper, nobody much cares where the
line is.

When the Adirondack Survey tried to find the SE corner of Franklin
County, there was a 900 foot error of closure, giving rise to the bent
corner at http://www.openstreetmap.org/#map=14/44.1352/-74.0731. The
surveyor who struck the modern line in the 1870's (reporting his 900
foot error of closure) found two previous surveys of the 18th century
land grand line that became the county boundary - about 4500 feet
apart! (And neither of the two previous surveys actually succeeded in
striking and monumenting the entire line.)

Since most of the land is uninhabited, and what isn't forbidding
mountains is sucking swamp, it's just never been worth anyone's time,
expense and danger to establish formal borders. When I'm working on
cadastral data from that part of the world, I tend just to ignore
topological inconsistencies unless they're more than a few hundred
feet or actually located within a village.

I still do want to track down the problem at
http://www.openstreetmap.org/#map=14/44.2421/-73.9544 - that overlap
between John Brown Farm and the state forest can't be right. I just
haven't had the bandwidth to pursue it.