From GNP web site
The earliest the Going-to-the-Sun Road could be accessible for its entire length is June 21, 2013.
(earliest DOES not mean that it will open on that date ~ just that IF the road is cleared of snow by then that it will open)
September 22, 2013 - The last day to drive the entire 50 miles.
September 23, 2013 - A section of the road will close to vehicle traffic to accommodate accelerated road rehabilitation. You will still be able to drive to Logan Pass, most likely from the West Entrance.
October 14, 2013 - The last day to drive to Logan Pass.
October 15, 2013 - The alpine section of the road will be inaccessible to vehicles.
For me this will be a nice change regarding Logan Pass in the fall since I live on the west side of GNP.
Many Glacier will still be open by way of RT 2.
From the west, that route is faster even though it is longer.
montana slow hiker