[alistairSH]

Also, if you look closely, many of the boundaries are just dirt path, not maintained road. And some don't have roads - it just appears that way from above because one crop/field ends and another starts.

But, yeah, the amount of roads, even just basic gravel or dirt double-track, is pretty amazing. I knew some of it existed, but didn't quite realize it spanned the entire middle third of the US until just now.