I don't think that #8 is Gettysburg. The 2005 annual re-enactment there was a week earlier on July 1 to 3. Doubt that even TAR or CBS has enough clout to get all the re-enacters to come back on July 9 and 10. ONLY Civil War enactment for July 9 -10 is in Beverly,West Virginia - the Battle of Rich Mountain. An important battle which allowed the "free state" of West Virginia to leave the Confedercy. But it certainly isn't as big a battle as Bull Run, Antietum, or Gettysburg. But maybe TAR has more clout than I think.
Thought the mission was the Alamo, but does not match any pix I can find.
Could be Jackson Hole, Wyoming since we supposedly had a sighting of Phil there (but date was week after Niagara Falls sighting.
With the new Yellow and White route marker, perhaps the Niagara Fall sighting on July 31 is for real. Go back and check.
Alas, no Alaska scenes in teaser vidcaps. Sucks, there goes my theory. But looks like a lot of time travelling around the West for which we had no sightings.
Check again on Grand Canyon; doesn't seem to really be a canyon, more like the badlands of the four corners used in many early westerns.