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

[Toby Murray]

On Mon, May 30, 2016 at 11:09 PM, Jake <jakewins at gmail.com> wrote:
> I've been mapping a small section of National Forest, which straddles two
> counties; Boone and Callaway.
>
> On every map I can find - Boone Countys GIS dept., census.gov, US Forest
> Service - the county border strictly follows a river, Cedar Creek. However,
> on OSM, the boundary is shaped exactly like the river, but is shifted about
> a quarter mile north-east of it. Here's a small section to show what I mean:
>
> https://www.openstreetmap.org/#map=14/38.8117/-92.1427
>
> Now, I'm pretty sure this is a mistake - rivers move, but they don't shift
> in perfectly synchronized 40-mile segments like this.

Probably a mistake, but not one done in OSM. Eric suggested a
way-dragging accident may have happened but looking at the node
histories, it looks like this is the original location of these nodes
from when Ian imported them from TIGER boundaries.

>
> I'd like to find out how that boundary is actually legally defined, but my
> google-fu is not strong enough, it seems.
>
> US mappers - do any of you know what government body is the keeper of truth
> for Missouri county boundaries?

I think Kevin's comments about the NY counties may be more common than
you think. I believe the county border between my county and the one
to the east was disputed for a long time and may actually still be a
sore spot between them. It was originally defined as the course of the
Big Blue River. Since then, the river flooded and changed its course
dramatically. The area of land between the two river courses contains
a Walmart Supercenter that both counties want tax dollars from :)

But the official boundary as it stands follows the old course of the
river, even in the lake that is now behind a dam they built to prevent
future floods.

Toby