On August 21, 2017, a total eclipse of the sun will be visible in 14 states. More precisely, it will be visible in portions of these 14 states. Furthermore, some places will be better than others. Let’s try a few locations, using an interactive map from the NASA website:
http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2017Aug21Tgoogle.html
By clicking on any place on the map, a table of statistics pops up. Right now, the important figure is: “Duration of Totality”. Click on Murfreesboro, Tennessee, which is close to Nashville, Tennessee. Note that the duration of totality will be approximately one minute. Next, try a location near the red line above Nashville. You will find that totality is much longer here, over 2-1/2 minutes. For the place with the longest possible totality, click on the purple balloon marked “GD” (greatest duration). For this location, the total portion of the eclipse will be 2 minutes, 40.2 seconds. For the longest look at the total eclipse, this is the “best” place to be. All other places will have shorter times of totality.
In summary, one must be between the purple lines to view a total eclipse, and the closer to the red line, the longer it will be visible. Finally, click on a location outside the purple lines, like Cincinnati or Louisville. The pop-up indicates that the eclipse will be partial, not total.
The word “best” can be misleading. For this eclipse, the location with the “Greatest Duration” is a wooded area, so viewing the eclipse may be difficult, if not impossible! Fortunately, there are many locations which have a very long duration of totality. To find them, click on places on the red line.
In addition to duration of totality, your “best” location will depend on many things, like how far you can travel, weather, and lodging. Above all, traffic jams must be avoided. Millions of people will be interested in this event, but the roads can’t handle all of them at once!
I have booked a motel room in Western Missouri, close to the “red line”. This location is reasonably close to our home in Michigan, and has a good history of clear skies in August. As I plan, I may find a better place, but I have a good “fallback” location.
Enjoy your planning!
John
Real Simple Astronomy 
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