OpenStreetMap
maybe it's because of the automated import (tiger for US and recently geobase for Canada) but the border is there 4 times at many place. I took a random place between Montana and Alberta ( osm.org/?lat=48.9952&lon=-110.647&zoom=14&layers=0B00FTF ) where I get those way:
osm.org/browse/way/15808114
osm.org/browse/way/30114504
osm.org/browse/way/24307864
osm.org/browse/way/16799216
so as I understand there is
one from national US border from tiger
one for the county border(source = county_import_v0.1_20080508235444)
one for the Alberta border from geobase
and finally one thats got almost everything (well except county) and as been make manually
to add to this there is almost 200 meter between the 2 farthest wich cause problem as some place (a street between theme...)
so what can we do about that, it more than 5000 km of border (and I didn't check the Alaska or any other border from US or Canada, but I looked in Europe and there haven't any problem like that?
Discussion
Comment from rtdg on 1 May 2009 at 19:17
There have been some discussions on the talk-ca list http://lists.openstreetmap.org/pipermail/talk-ca/, and the talk-us list as well, about it so it is a known issue. The conclusion that I believe they came to was that the GeoBase border was probably the most accurate and should be seen as the one to keep. Although the border between Canada and the US is nominally at the 49th parallel in the area there are actually markers that are used as reference points and they are not always as exact as they could be. And since there is really no way to correct unintended errors that occurred when they were marked the border does vary slightly from the intended location. Over time there is going to have to be an effort to clean up the border to ensure that there is really only one marked. Also the border for Alberta should actually be the international border as well.
For more information look at the thread started with http://lists.openstreetmap.org/pipermail/talk-ca/2009-March/000910.html and going well into April.
Comment from Candid Dauth on 3 May 2009 at 16:51
Here in Germany, we have a similar problem. At least in Landkreis Miesbach, there are two borders to Austria: one from the Landkreis border import, which is really detailed, and one with the source CIA World Databank II. Unfortunately, the CIA border only consists of nodes, and those are not connected by a way. Fortunately though, they all have a source tag, so it would be rather easy to delete them.