The maximum duration of darkness for the August 21, 2017 total solar eclipse and its location has changed to Illinois near a small town called Goreville at 2 minutes and 41.6 seconds according to Xavier Jubier. The information on Wikipedia is still showing the old Kentucky data.
You may be aware that the NASA solar eclipse website was taken down for a week back in February with a redirect to the United States Naval Observatory. Why? I guess NASA told Fred Espenak to update his information before the site would come back online. His information is now updated up to a point. If you look at his current orthographic maps, he now puts a full date at the bottom of the map. Before that, he would only put a date of Fri, July 2, with no year. Here is the link to his main page http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2017Aug21Tgoogle.html
Espenak rewrote the definition of "greatest eclipse." He separated out the term "greatest duration." His old definition used both terms in one paragraph and described GE and GD as being "virtually" in the same geographical location. Espenak was aware this is not the case based on the recent data obtained from the Kaguya/LRO lunar limb profile. Here is the link to the glossary http://eclipse.gsfc.nasa.gov/SEhelp/SEglossary.html
Strangely, his current orthographic maps do not show the two locations (GE and GD) on the map but only a description of the "Circumstances at Greatest Duration" http://eclipse.gsfc.nasa.gov/SEplot/SEplot2001/SE2017Aug21T.GIF . Now if you go to Xavier Jubier's map, it shows GE and GD on the map. Here is the link to Jubier's map http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017_GoogleMapFull.html Also note that Espenak now puts a full date of February 22, 2014 on his orthographic map!
Wikipedia does not mention the United States Naval Observatory's (USNO) findings http://aa.usno.navy.mil/data/docs/Eclipse2017.php They have a maximum duration of darkness at 2 minutes and 44.6 seconds -- some six miles south of Carbondale Illinois in the Shawnee National Forest. I think Jubier's location is also in the Shawnee National Forest, but 19 miles to the east of USNO's location. Also USNO does not use the terms GE or GD -- they just use the term "maximum duration." The lengths of times are now 3 seconds apart in duration of darkness.
Again, the information on Wikipedia about the August 21, 2017 solar eclipse is incorrect. Both NASA and USNO are now pointing to southern Illinois for the place of maximum duration of darkness.