This M Loop is the longest hiking trail in the Highland Forest County Park system.  It is a mild trafficked loop. With technical terrain, creek.  Is extremely muddy especially early spring. Great views and so peaceful. 

Trails map:  https://www.onondagacountyparks.com/assets/Uploads/HF2016TrailMaps.pdf

Ireland's longest coast-to-coast walking and cycling trail, 1000km/620miles long, covering the length of the island.  The Ireland Way joins the newly developed Beara-Breifne Way to the Ulster Way on the island of Ireland. The trail goes from the Beara Peninsula in County Cork, Republic of Ireland to Ballycastle, County Antrim in Northern Ireland.

https://www.theirelandway.ie/

This trail is a rail to trail in Winnebago and Boone county. The trail is primarily crushed limestone but has a couple of spots where it is paved and has some road crossings. The trail goes past the historic Stone Bridge and goes by several other nature preserves and farmland. The trail is continuous and the only reason it changes names is because that is where it goes from one county to another. The trail itself is well trafficked especially near Roscoe, Rockton, and the other smaller towns along the trail. It is also the longest trail in the area (at least to my knowledge.)