On 2012-12-31 12:30 PM, stevea wrote:
However, there are boundary polygons in OSM which are an odd duck in the
USA: a notable one is Census Designated Places (CDPs), which came from
the TIGER import. These are a bit like cities in that they are often a
similar size and population of a town or rather small city. But they
are not strictly cities, in that they are derived from the federal
government (not "negotiated" with a state government like a city which
is or has incorporated) crafting them for statistical purposes. CDPs
have no legal basis as incorporated cities do. In fact, many of the
residents of these areas may not even be aware of the boundaries of
their own CDP. However, CDPs are useful, as they often give name and
shape to a place or area which otherwise might not have one, and
frequently the CDP yields the only boundaries for doing so.
In other words, CDPs (and others, see below) really are administrative
divisions in the USA, we just don't often think of them that way, and so
we don't (often) classify them into a hierarchy. I do believe it is
proper and useful to do so, but of course we should strive to get to as
correct as a consensus/result as we can.
I'd argue that not all governmental boundaries need to be tagged as
boundary=administrative. In Ohio, we've started to retag CDP boundaries
with boundary=census and place=locality but without admin_level. [1][2]
They still show up in Nominatim as localities.
As you mentioned, CDPs' boundaries have no legal status. There is a
reason most residents aren't aware of their CDPs' boundaries: the CDPs
themselves are a statistical convenience rather than a fact on the
ground. Yes, they were drawn up by an administrative agency, but nothing
is administered differently inside them. Unless a data consumer cares
about census delineations in particular, place=hamlet POIs are more
appropriate for population centers without formal boundaries anyways.
In states that give civil townships some authority, they are much more
important to the identity of an unincorporated area than CDPs. The TIGER
boundary import excluded Ohio townships, so Vid the Kid and I have been
painstakinglly filling them in.
I have edited
http://wiki.openstreetmap.org/wiki/United_States_admin_level to reflect
the reality of this more complicated picture in the USA, some states
which don't cleanly follow the 2/4/6/8 model, and at least some of these
"more federal" entities. (There are also LAFCos in California, as well
as COGs in many states, which are state-defined, in addition to MPOs,
which straddle a local/federal level, and PSAs, CSAs, MSAs, and µSAs,
defined by the executive branch of the federal government).
PSA, CSA, MSA, and µSA boundaries have more bearing on reality than
CDPs, but again they don't correspond to any government agencies, so
boundary=census would still seem to fit these divisions better.
At any given place in the U.S., you're likely to be subject to a variety
of government agencies with crisscrossing jurisdictions. Some of these
boundaries matter more than others. For example, in Ohio, it makes a
whole lot of sense to map townships, even if they sometimes cross city
limits. But if I mapped every water board, school district, fire
department, and sewer district in my area, the result would be an
illegible map. If we considered congressional and state legislative
districts to be "administrative" as well, it'd be even worse.
COGs and MPOs, on the other hand, often map very cleanly to county
lines, as do state DOT districts, state patrol districts, and so on.
Perhaps these boundaries matter a lot more in some states than others,
but they still seem like highly specialized data that's more appropriate
for a mashup than the OSM database.
As a starting point, we can keep this discussion simple and decide
whether a CDP might rightly be assigned an admin_level of 5, as it is
both a federal and quasi-local entity which correctly "lands in the
middle" (below state but above county), or whether it might actually be
lower than a city (but implying subordinate to? -- doesn't seem
correct...) with an admin_level of 9.
Just because they can cross county lines doesn't necessarily mean they
should sit above counties. Some states allow cities and villages to
cross county lines, but they're still admin_level=8.
SteveA
California
[1] http://wiki.openstreetmap.org/wiki/Ohio#CDPs
[2] http://taginfo.openstreetmap.org/tags/boundary=census
--
Minh Nguyen <[email protected]>
Jabber: [email protected]; Blog: http://notes.1ec5.org/
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