I have been working on placing the boundary in the correct location, or at least as “correct” as is technically possible. Before I started this, the boundary was mostly mapped using (as best as I can tell) data from the Canadian “Canvec” and “Geobase” datasets along the St. Croix River, and the NAD83 coordinates published by the International Boundary Commission in Passamaquoddy Bay. This was roughly correct in most cases, but some in some places the boundary is/was completely on the wrong side of the river. Essentially, we have been using the edge of the Canadian hydrography dataset as the national border.

The actual border

The actual position of the border is defined by the Treaty of 1908, as modified by the treaties of 1920 and 1925. The text of these treaties can be found on the website of the International Boundary Commission. The general message from actually looking at them is that the determinations and demarcations of the IBC are “definitive”… the boundary is where the IBC says it is, in their official publications and on their official maps.

These publications can be found in scanned form on HathiTrust. All but Special Reports 8 and 9 predate the adoption of the North American Datum of 1983… this means that the official position of most of the boundary is actually defined in either the pre-1927 United States Standard Datum, or the North American Datum of 1927.

While the IBC does publish a shapefile of the boundary (in NAD83) and a “coordinate listing” for each section in both NAD27 and NAD83, these files are of limited use. They are explicitly stated to be not official, and I have found obvious typos that would locate the border miles out of position. Also, the given NAD83 coordinates are unhelpful since they do not state which “realization” of NAD83 they are in. OSM is capable of storing coordinates to a degree of precision at which this makes a difference.

Obtaining correct coordinates

… See full entry

Just a quick note, re my previous one about the ‘project’ to fix the duplicate search results for US counties by linking the boundary relations.

I’m keeping a ‘informal’ worklist here… osm.wiki/User:Revent/Counties because I’m OCD and want to know they are all done.

Currently we have over 1100 counties done (out of about 3400), so approximately 1/3. More volunteers to do your local state welcome! :P Letting me know that an area has been done would also be nice, so I can mark it off the list.

ToeBee has a nice blog post about an efficient ‘workflow’ for fixing a state with JOSM here… http://ksmapper.blogspot.com/

After lots of Googling, talking on IRC, and futzing with things, I’ve learned how to get Nominatim to properly link boundaries and place nodes, and thus get addressing to work correctly (at least on the county level). I’m assuming this also works at the city level, though I’m still in the process of fixing Texas counties and haven’t tried it with cities yet.

The ‘key’ is in the names and alt_name, and using the ‘label’ role on the boundary relation. For example, “Anderson County, Texas” has ‘name=Anderson County’ and ‘alt_name=Anderson’, while the county node has ‘place=county’ and ‘name=Anderson”. Also, importantly, the county node is a member of the boundary relation, with the role ‘label’.

This is how it looks in Nominatim when working right…. the boundary: http://nominatim.openstreetmap.org/details.php?place_id=98191762 the county node: http://nominatim.openstreetmap.org/details.php?place_id=9162125655

This is an example of one I haven’t fixed yet, that is still working wrong… the boundary: http://nominatim.openstreetmap.org/details.php?place_id=98029496 the county node: http://nominatim.openstreetmap.org/details.php?place_id=1600889

As you can see, in the one that works right, the county node is listed as a ‘linked place’ in the boundary relation entry, and all of the places in the county are ‘addressed’ to the boundary relation instead of split between it and the county node. Also, if you look at the places located in the county, such as http://nominatim.openstreetmap.org/details.php?place_id=2769902 you can see that Nominatim is no longer having to ‘guess’ at the county addressing, as it’s now explicit.

I’m also setting the boundary ways as “boundary=administrative and admin_level=6”, but I don’t think this is really essential…it’s more a backup for if those keys get removed from the relation.

… See full entry

Spam, sorry, nevermind. I though the recent entries thing would chop it off. My apologies.

(chopping this off into an offline file)