Congrats.
Probably the longest I've ever walked on the AT is the pedestrian bridge (attached to a RR bridge) that crosses the Potomac River at Harpers Ferry. :)
I've also seen highway crossings of the AT at Newfound Gap in the Great Smokies on Route 441; I-70 in MD where that road goes under the AT (there's a pedestrian bridge for the AT there too), and one or two places in PA (not counting the few times I went through the Lehigh Tunnel on the PA Turnpike NE Extension, which goes under the AT).
Yes, I've read Bryson's book (my library's copy) and it is a bit of a ripoff.
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Blue Mountain was a horrid stretch the year I hiked. It was in the 100s and all of the springs were dry. We sipped our way through our canteens and really struggled for a couple of days. That was the most miserable part of the trip. (Next was Vermont, which isn’t nicknamed Vermud for nothing...).