<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><br></div><div>On 2013-01-09, at 12:58 PM, Clifford Snow <<a href="mailto:clifford@snowandsnow.us">clifford@snowandsnow.us</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Wed, Jan 9, 2013 at 8:27 AM, Andrew Guertin <span dir="ltr"><<a href="mailto:andrew.guertin@uvm.edu" target="_blank">andrew.guertin@uvm.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div>I plan to import VT town boundaries from that file at some point, but<br>
was not planning on touching any of the state boundaries (except to<br>
connect town boundaries to them). I'd be interested to know how well<br>
that data source matches others for the state boundary, too, though.</div></blockquote></div><br>Paul Norman got me thinking about the BC/Washington State border. Comparing Washington State's border files with TIGER data you'll find discrepancies. I emailed our state's GIS group. Here is the response I received.</div>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div class="gmail_extra" style=""><p style="font-family:arial,sans-serif;font-size:13.333333969116211px"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">While I cannot speak to the construction of the <span>State</span> polygons in the TIGER shapefile I can relate why I think the <span>State</span> version is more accurate. The version created and maintained by the <span>Washington</span> <span>State</span> Department of Natural Resources utilizes positions of actual international boundary monuments that have been coordinated by the National Geodetic Survey (NGS) or by other surveys performed by licensed land surveyors.</span></p>
</div><div class="gmail_extra" style=""><p style="font-family:arial,sans-serif;font-size:13.333333969116211px"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">I did some spot checking where we have monument positions and found the <span>State</span> line to be more accurate than the TIGER representation. I also spot-compared the lines to existing features, such as roads running parallel to the boundary; see a screen shot below where the red line is TIGER and the green line is <span>State</span>. The road in question is in fact in Canada, but the TIGER boundary zigzags from one side to the other.</span></p>
</div><div class="gmail_extra" style=""><p style="font-family:arial,sans-serif;font-size:13.333333969116211px"><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.44444465637207px">It looks like there are some other differences between the </span><span class="" style="font-family:Calibri,sans-serif;font-size:14.44444465637207px">Washington</span><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.44444465637207px"> version and the TIGER shapefile along the </span><span class="" style="font-family:Calibri,sans-serif;font-size:14.44444465637207px">borders</span><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.44444465637207px"> of Idaho and Oregon as well. For </span><span class="" style="font-family:Calibri,sans-serif;font-size:14.44444465637207px">Washington</span><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.44444465637207px"> we use survey data where available here as well, but I did not check as thoroughly to try and figure the differences out.</span></p>
</div></blockquote><div class="gmail_extra">
<div style="">You might want to check out all of your state's boundaries against Quebec and neighboring states. I haven't done anything with Washington State. I'd say something about a rainy day project, but it has been raining here for a while and will continue until July. </div></div></div></blockquote><br><div>On the west coast the Canada/US border is defined as the line formed from a bunch of survey points. These points can be surveyed or seen on imagery. I used the IBC positions for the points which are far more accurate than anything I could of done. In theory they could be improved, but the accuracy limit of the DB might be an issue.</div><div><br></div><div>I verified the data with multiple other sources and they all agreed within the limits of the sources.</div><div><br></div><div>The tricky part was making the lines straight where they joined up with cities, etc.</div><div><br></div><div>I would not suggest using state data for the Canada/US border.</div></body></html>