Those interested in the 2017 solar eclipse path across the US might also wish to view an earlier Reflector article in which the use of the polygon feature in the SMP range page was introduced, and in which a more accurate set of points (which you can copy with the mouse and paste into the range page dialog) for the region of eclipse totality was given: http://reflector.sota.org.uk/t/smp-range-page-update-3/14534 .
Rob