If all of you want to have some fun with jurisdictional boundaries, take a look 
at College Corner, OH/IN.  It is a village purposefully straddling the OH/IN 
state lines with the main street being the state line.  It has two zip codes, 
is in three counties (two in OH, one in IN) and school district issues to 
match.  It puts paid to a lot of ideas we all have about jurisdictional 
hierarchies and boundaries.  Delmar in Delaware/Maryland has similar, though 
not quite as complicated issues.  I'm sure there are other examples


Kerry Irons
Adventure Cycling Association

-----Original Message-----
From: OSM Volunteer stevea [mailto:stevea...@softworkers.com] 
Sent: Tuesday, July 11, 2017 2:19 PM
To: talk-us <talk-us@openstreetmap.org>
Subject: Re: [Talk-us] Differences with USA admin_level tagging

I'm glad Adam brings up the topic of Gores, as I'm also unclear on how such 
"holes" get "punched into" larger (multi)polygons via tagging.  For example, I 
am "sort-of-sure" (but not positive) that in Vermont, a "gore" (or grant, 
location, purchase, surplus, strip...usually the result of "leftovers" from 
survey errors) get a tag of admin_level=4 to accurately reflect that the 
governmental administration happens via state-level bureaucracy.  Yet, like 
Adam, I also have the nagging feeling of "smells wrong," because I don't 
understand the mechanism by which such a "hole" is "punched into" the state 
like this to the exclusion of the lower-level entities (like a Town).  
("Sort-of-sure" doesn't feel good enough to me, so I seek clarification).

Yes, we use multipolygon relations to explicitly do this with outer-role 
polygon(s) and inner-role "hole" polygon(s).  But we are not using an explicit 
multipolygon relation here, we are just expecting the mechanics of OSM (like a 
renderer) to "figure this out."  Similar things happen, for example, with 
Indian Reservations "punching holes" in state and/or federal jurisdictions in 
places like Arizona and Oklahoma (to name but two).  So, too, perhaps with 
military reservations, though that is not as good an example, as I don't think 
we regularly tag those with admin_level=2 to explicitly assert 
federal/national-level jurisdiction on those, though we could or might.  An 
additional wrinkle in that example is that since the 1950s, the USA has taken 
pains to extend "full concurrent jurisdiction" on all federal enclaves such as 
military reservations, implying that BOTH admin_level=2 and admin_level=4 might 
be applied to federal enclaves such as military reservations.  Our 
US_admin_level wiki mentions this, but it is left unclear on the correct 
approach we might take.

So, in short, I am asking anybody who is able to do so to please clarify:  
without using a multipolygon relation, is it correct within OSM to tag, say a 
very large "lower 48 states" polygon with admin_level=2 AND ALSO tag 
admin_level=2 on, say, a national_park inside of it (which is itself inside of 
another polygon called a "state," with admin_level=4)?  Does "the right thing 
happen" if/as we do this, for example, would a renderer know to draw this as a 
"hole," without using a multipolygon relation?  Are semantics applied correctly 
to the map such that the national_park is federal, even though it is within a 
state?

Guidance by knowledgable people with real answers might guide us on a number of 
these situations, not just "Gores" (et al) but other kinds of "hole" tagging 
without multipolygons.  We do strive to do this correctly!

Thank you,

SteveA
California


Adam Franco writes:
On the "Gores" point: In Vermont, while these do not have any administrative 
infrastructure and are managed by the State, they *are* surveyed and named 
places with defined borders (shared with their surrounding Towns). As such it 
likely makes sense to preserve them as multipolygons each with their own name 
and detail tags. Since these areas are exclusive of Town/City areas, it might 
make sense to give them the same admin_level even though the mechanisms of 
administration are different.
They aren't States themselves, so a border=administrative,admin_level=4
smells wrong. I can't speak to the situation in Maine.




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