I actually learned of an old alignment of US 322 in central Pennsylvania through someone who I had talked with during a hike I took today in Manchester, Vermont. The old alignment is now a lengthy hiking trail through the Seven Mountains between Potter Mills and Milroy. I'll need to do some more research on this before I go, but from what I've read so far, the old alignment could make for a nice day hike.
http://pennsylvania.sierraclub.org/moshannon/OTT/OTT09-04SevenMtsRestArea.htm (http://pennsylvania.sierraclub.org/moshannon/OTT/OTT09-04SevenMtsRestArea.htm)
That sounds like an really good trip. I see the old alignment went through the Laurel Creek Reservoir.
That could've been a doable hike when I was still in DC. As it was (as far as PA stuff), I was only able to bike the abandoned PA Turnpike east of Breezewood.
That section became abandoned in 1968 when the expressway alignment was completed.