[Tagging] Admin Boundary admin_centre or label roles

[Minh Nguyen]

Vào lúc 09:04 2021-09-29, Paul Johnson đã viết:
> The city hall would be the correct thing to have the 
> "admin_centre" role.

Apart from the multipolygon processing problem Sarah points out, this 
would also be inconsistent with the semantics of admin_centre for 
nonmunicipalities. We wouldn't tag the White House, Capitol, and Supreme 
Court as the three admin_centres of the U.S., even if they were nodes.

The operator=* and operator:wikidata=* keys are more appropriate for 
explicitly indicating which buildings are used for the administration of 
the municipality. It's also pretty common to just tag townhall:type=* 
and let data consumers infer the relationship spatially, though this 
would be ambiguous in some cases.

> For "label", I usually pick the node representing 
> the city center, and if I know the address origin location (where all 
> the addresses in that town count away from), I'll put that node as close 
> to that as practical.  If it's counting away from another location or 
> it's not clear, I'll aim for the center of mass (since it's not uncommon 
> for towns and cities to have long, spidery reaches along a road with 
> everything on either side of the road not being in town, but the road 
> itself is).

Yes, these are some of the many ways in which a city's "proper" center 
would be determined locally in the U.S. I happen to live in a city that 
spreads its tentacles all over, and the city hall is just to the east of 
the downtown district, but the proper city center is clear because 
there's only one intersection in the whole city where North * Street, 
South * Street, East * Street, and West * Street all meet.

Sometimes it can be more idiosyncratic. I used to live in a city that 
began along a river and grew northward, the city hall is just to the 
west of the central business district, and the commonly accepted city 
center is a famous fountain in a public square. (Nevermind that the 
fountain itself moved some 150 feet several years ago.)

> Be aware that city halls are optional and often not something that 
> formally exists.  I'd hazard to guess that in a decent majority of towns 
> and even some cities in Oklahoma, it'd be a little weird to tag 
> someone's garage or house as that'd be the closest a lot of places get 
> to having a town/city hall. In fact, please don't map such cases unless 
> they're openly advertising that their home is city hall; they have 
> private lives, too.  While I believe Oklahoma to be a particularly 
> extreme example of this phenomenon (we are where the phrase "dirt 
> farming poor" comes from 90 years ago, after all), my experience in 
> other parts of the US and Canada suggests it's endemic in smaller 
> communities across the continent.

Similarly, I know of a few Ohio townships that have no physical presence 
other than a meeting in a different trustee's garage each month. 
Obviously no one would map all three trustee's homes as 
amenity=townhalls. The more common case is a township whose 
administrative "building" is a trailer within a village within the 
township, sometimes next door to a much larger village hall. Neither the 
trailer nor the village would be part of the township relation, because 
in that state, there's no such thing as a "township seat" like there is 
a "county seat".

And then there's the city of 
<https://en.wikipedia.org/wiki/South_Park_View,_Kentucky>, which has 
welcome signs and some businesses but no population and an official 
mailing address 60 miles away at the state capital. Government org 
structures can get weird sometimes; it's best to leave those intricacies 
to a resource other than a map.

-- 
minh at nguyen.cincinnati.oh.us