We have dozens of these trails here in Illinois. They’re built on old railroad rights of way. One can walk from very near Lake Michigan in downtown Chicago all the way to the Iowa, Wisconsin, Missouri, Indiana, and Kentucky borders.
Link to map here:
https://www.dnr.illinois.gov/publications/documents/00000642.pdf
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That “Tunnel Hill Trail” in Southern Illinois crosses exceptionally varied terrain: Flat (for miles) farmland, rocky bluffs, bottomlands, hills, wetlands, and an out-and-out swamp. And it includes trestles over valleys and a kinda cool old railroad tunnel. It is used by many hikers and bikers.