[Talk-us] Characterizing Systematic Errors in Hawaii and US Pacific Island Data

Scott Atwood scott.roy.atwood at gmail.com
Fri Oct 2 22:15:48 BST 2009

On Fri, Oct 2, 2009 at 1:24 PM, Richard Weait <richard at weait.com> wrote:

> On Fri, Oct 2, 2009 at 3:39 PM, Scott Atwood <scott.roy.atwood at gmail.com>
> wrote:
> > Once again, if the political boundaries are supposed to correspond
> exactly
> > to the shoreline data, the whatever is done for Kohoʻolawe and Lanaʻi
> should
> > also be done for these three islands to correct the political boundaries.
> >  The rest of the data can be easily cleaned up manually.
> When the boundary and shoreline correspond, should they be on the same way?
> boundary=administrative
> admin_level=?
> natural=water

I'm honestly not sure what official boundaries, if any, correspond to the
coastlines in the state of Hawaiʻi.  I know that users yellowbkpk and/or
elyk appear to have imported data from source county_import_v0 that roughly
corresponds to the coastlines, that is tagged as both state and county
However, Wikipedia cites the US Census Bureau as saying that Maui county has
1159 square miles of land and 1240 square miles of water, which suggests
that at least this one federal agency uses a boundary for Maui County that
doesn't follow the shoreline of the islands that comprise the county.
 Likewise, Wikipedia lists Hawai‘i island with an area of 4028 square miles,
but Hawaiʻi County with an area of 5087 square miles.

According to this New York Times article from 1991 (
since 1990 the U.S. Census Bureau includes coastal waters out to 3 miles as
part of the area for each state.  According to international law, a
country's sovereign territory extend 12 nautical miles from the coastline.
 The same international law also defines additional boundaries of decrease
sovereignty at 24 nautical miles and 200 nautical miles.

So there are quite a number of potential or actual political boundaries
exist around the islands of Hawaiʻi.  I suspect that a mapping project such
as OSM ought to include all of them in its data.

As nearly as I can tell the shoreline does not currently have any official
status as a political boundary.  I *think* the official county, state, and
US boundaries in Hawaiʻi are at 3 miles out from the coastlines.  That would
be a very difficult boundary to draw manually.  Is there any way to
programmatically create such a boundary based on the existing shoreline
data?  Surely this problem must have been encountered and solved before for
other jurisdictions with territorial waters.


Scott Atwood

Cycle tracks will abound in Utopia.  ~H.G. Wells
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