[Talk-us] Proposed (partial) import: New York State minor civil divisions.

[Kevin Kenny]

The OSM representation of minor civil divisions in New York State has
several problems.

(1) About a third of the cities, towns and villages, most of them in the
northern and western parts of the state, are missing entirely - apparently
the TIGER and USGS imports never succeeded in importing them.

(2) Many administrative boundaries in TIGER were simply incorrect. The
state's database appears to be more trustworthy; for example, there was
reasonable alignment between the state's data and the county's tax rolls in
the case described in https://www.openstreetmap.org/user/ke9tv/diary/391486.

(3) Few, if any, of the minor civil subdivisions' populations have been
updated as of the 2020 census.

(4) Some boundaries were conflated with watercourses that have changed
course abruptly in Hurricanes Irene (2011), Lee (2011) and Sandy (2012).
Because these changes were avulsion (abrupt change resulting from a
specific catastrophe) rather than accretion (gradual deposition of
sediment), erosion, or reliction (exposure of land by declining water
level), they often did not move the boundaries, even though the
watercourses have since been edited. These moved watercourses must be
deconflated with the boundaries, and the boundaries returned to their
proper places.

New York State maintains authoritative data sets for minor civil divisions
at http://gis.ny.gov/civil-boundaries/.  The license for these data is the
state's standard open data license, available from
https://data.ny.gov/dataset/OPEN-NY-Terms-Of-Use/77gx-ii52. This license
governs several New York data products that have already been imported;
most notably the Department of Environmental Conservation lands and
campgrounds, the state parks and state historic sites, and the statewide
address point data.

Starting from the shapefiles available from gis.ny.gov, I've succeeded in
making a topologically-correct OSM data set. It's available for inspection
at https://kbk.is-a-geek.net/attachments/20211215/topo_cities_towns.osm.pbf

The tag, 'user:ke9tv:fid' present on the ways is there because the
conflation process that I'm using needs to know, for the ways that are
already done, what the unique ID of the way was in the source database.  It
will be removed from OSM at the conclusion of the import. The other odd
tags are

gnis:feature_id - Same meaning as in TIGER: the GNIS ID of the feature in
question; a foreign key into many government databases.
nist:fips_code - The FIPS code of the feature in question; another
important foreign key that ties together government databases.
us:ny:swis - The code for the feature in New York's Statewide Information
System, again a foreign key into many external databases.


The idea with this file is that I'll go through it, town by town. (There
are 1600 towns; I should be able to stitch things together in a few weeks.)
The workflow will be to copy-and-paste the relations for the municipalities
into JOSM one at a time, do manual conflation of the borders, do manual
conflation of the relations, update populations, add Wikipedia and Wikidata
tags, and upload. I've only done one township - Champlain, New York - so
far, as a test case.  It can be seen at
https://www.openstreetmap.org/relation/13552232 .  Note that the two member
ways https://www.openstreetmap.org/way/1012328548 and
https://www.openstreetmap.org/way/1012328549 are already split, to allow
seamlessly anchoring the boundary between Chazy and Mooers, the next
bordering towns.  The villages of Champlain and Rouses Point are also done.
The latter shares boundaries with the township, the county, the state and
the United States.

If there are any serious problems with this project, I'm prepared to revert
or amend the two changesets that have been committed so far.

Given the amount of manual work that's being done here, this hardly
qualifies as a 'mechanical edit' - but given that the external data source
is a specific file that we haven't used before, I thought it wise to run
this by the community.  Please let me know of any objections!
-- 
73 de ke9tv/2, Kevin
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