> On Nov 10, 2015, at 5:59 AM, Greg Troxel <[email protected]> wrote:
> 
> 
> Tod Fitch <[email protected]> writes:
> 
>> What is a “city” in US specific OSM terms?
>> 
>> I prefer a postal city definition as that is the most useful for
>> routing purposes which I feel is the primary use of address data in
>> OSM. Or are we dealing with some other concept of addr:city?
> 
> I see it as fairly clear that addr:city is about administrative
> boundaries and what the local civil government considers to be legal
> physical addresses (vs mailing addresses).
> 
> In Massachusetts this is very clear; every bit of land is in a city or
> town, and there are (mostly) granite markers at the corners.
> 
> In states with unincorporated areas, it seems like there are areas with
> cities, and then areas beyond the city where some rules apply, and then
> areas that are in a county but not really in a city, so I can see that
> this is complicated.
> 
> It would be interesting to ask the assessors or the police/fire
> department or PSAP operators how they see addresses and cities in these
> areas.
> 
> I would suggest that if we want to tag postal addresses vs legal
> addresses that those have tags that are explicitly about postal.

This is getting away from San Diego address import updates, but I think this is 
a topic that needs to be clarified. What is a city for the purposes of 
addr:city tag values in the US in the OSM database?

For what it is worth, in California (at least in the counties I have lived in) 
the legal description of a piece of land is a designation of the map book, page 
and parcel number in the county records. I believe the street name and number 
as well as the city name and ZIP code on the parcel can change over time and it 
does not change the legal description. So if addr:street, addr:housenumber, 
addr:city, etc. are not set to the legal description what should they be set to?

Here are some places that I am pretty familiar with having either lived in them 
or with extended visits to family who live in them.

First, Tucson, AZ. Tucson is an incorporated city with legally defined 
boundaries. When I lived there (many years ago) we didn’t actually live within 
the city limits but in a residential subdivision between the city and the 
mountains to the north. The “city” used in the address for all those years was 
always “Tucson” even though we were never within the incorporated city limits 
and civil administration was through the county. There were no other 
incorporated cities or towns near by, so if Tucson was not an option for city 
name then the only logical choice would be an empty or blank. Nobody ever left 
the city portion of an address field blank when filling out forms, “Tucson” was 
always used but it fails the administrative boundary test.

Second, Oracle, AZ. This town has existed for over 100 years but is not 
incorporated and, near as I can tell, has no official boundaries. There is a 
CDP for it but the boundaries on that do not seem to match what the locals 
consider the town. It has a volunteer run library, a volunteer fire department, 
a post office, a county administration office including court facilities and a 
sheriff’s substation. All with “Oracle” in their names and when you call 911, 
the PSAP wants to know that you are “in” Oracle (no enhanced 911 in the area 
yet). So it passes the “duck test” for a town. But it has no administrative 
boundaries and no concrete or granite boundaries at the corners and civil 
administration is handled from the county seat (about an hour drive away) so it 
fails the formal administrative boundary test. What value should be used for 
addr:city tags in that area? “Oracle” seems correct to me.

Third, Sunnyvale, CA. seems to more closely match the Massachusetts model as 
the area is pretty well built up and has relatively clear boundaries with 
adjacent incorporated cities (Mountain View, Los Altos, Cupertino, Santa 
Clara). But it turns out that there are small parcels of land surrounded by the 
city which are not legally part of it and are under county jurisdiction. I 
don’t really know how fire and police response to those parcels work, I suspect 
the county has an agreement with the city to have the city respond but I don’t 
really know. Walking or driving by them you will not see any visible indication 
that the land is not part of the city. It is only when a builder decides to put 
something big on it do you find out that the land isn’t officially in the city 
and the permit and planning have to be approved by the county (almost always 
with city input as an interested party). So what OSM city name should be used 
on those parcels (assuming you can identify them on the ground)? “Sunnyvale” 
seems like the right answer to me but it would fail the administrative boundary 
test.

Finally, Los Angeles. The incorporated area for LA is huge and it surrounds 
other incorporated cities. But there are areas in LA like Woodland Hills, 
Chatsworth, Canoga Park, Van Nuys, and Studio City where the locals, when 
asked, won’t say they are in LA. They will give the local area name even though 
they are part of the city of Los Angeles. The postal address is also the local 
name. And the city of LA has even posted signs, similar to those you see when 
entering an incorporated city or town, indicating you are entering those 
locally named places. What should the addr:city name be?

So what is a good definition for what should go in the addr:city tag? If it is 
based on being within a formal administrative boundary then we may not need the 
tag at all as it should be easy for a data consumer to detect that. I have come 
to the conclusion that the addr:city is best to indicate what the locals feel 
their town name is. In the western US my impression is that has a high 
correlation with the USPS designation. Further, when dealing with any financial 
or government entity, it seems the city they want to hear about is the one the 
post office delivers to, not some subset or superset defined by a formal 
boundary of an incorporated town or city. So equating the post office town name 
with the OSM addr:city value seems proper to me.



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