[Talk-us] Differences with USA admin_level tagging

OSM Volunteer stevea steveaOSM at softworkers.com
Mon Jul 10 23:38:46 UTC 2017

Continuing my replies to this thread.

Greg Troxel writes:
The notion that Town and City are fundamentally different in
Massachusetts is incorrect.   I think that's the long and short of your
basis for commenting, but if I'm off please tell me.

Greg, Massachusetts' entry in US_admin_level's wiki table (the "Big Table") now reads (thanks, Peter Dobratz!):

4		5		6		7		8		9		10
Mass.	N/A		County	N/A		Town		Precinct	N/A
Mass.	N/A		County	N/A		City		Ward		Precinct

I believe this achieves harmony between what I have read/researched, what Peter said in the wiki's Discussion page, and what you say here, as both Town and City are admin_level=8, though they do diverge with 9 and 10 (hence, two "sub-rows").  Also, none of the six New England states has a "Township" (at admin_level 7, where it often lives; thanks again Peter).  I believe the table (in New England) agrees with your other "every bit of land is in exactly one municipal entity" concern.  (Almost, but not quite:  Vermont, New Hampshire and especially Maine have exceptions, these are noted in the Big Table's Notes; see Note 18).  If what the Big Table says (now) in Massachusetts isn't what you agree with, please continue to further clarify.  (No "hard time" taken here:  I think we have it about right!)

A subsequent post of Greg's suggests that "villages and hamlets are place names not administrative divisions."  The Big Table does not list those, so I think it's OK.  And, YES:  your "key point" that OSM has words (e.g. Town, City) with OSM-defined meanings, yet "each state may well use those same words to mean different things, and we have to be careful to separate local language and OSM language" is so very true:  a "land mine" potentially rife with misunderstanding and confusion.  This is why it makes sense to be precise and hash this out in our community.  In that context, one topic to have clearly emerged is that for "unincorporated areas," OSM is better served by a node with place=* tagging, rather than a (multi)polygon with boundary=administrative + admin_level=* tagging.  And the wiki so states, with "rule of thumb" values for the place=* tag.


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