The Badger State Trail is a rail trail running from the Illinois-Wisconsin border north to Madison. The route is almost entirely crushed limestone, but is paved for a few miles near the Madison terminus. It features the Stewart tunnel, a 1200-ft tunnel cut through solid limestone.  ~40 miles.

--submitted by Mikey Kartje

Note that Mikey Kartje ran *almost* the whole trail in 6h49m18s on 4/5/2020:

Hancock, MD is home to the narrowest pinch in the state. Barely 2.5 miles wide. This route is all on roads, and is slightly uphill if you travel northbound. There is a Strava segment for the route where times can be compared.

https://www.strava.com/activities/840939567/overview

- Submitted by Evan Daney

A technical route starting by the Emosson dam (Switzerland), finish in Servoz (France).
 

Submitted by Tito Nazar:

Start at the bus stop in Gaicht in the Tannheimer Tal. Ascent to the Krinnenspitze (2000m). Then continue to the Litnisschrofen (2068m). Continue to the Sulzspitze (2084m), the Schochenspitze (2069m), the Lachenspitze (2126m) and over to the Steinkarspitze (2067m) and finally the Rote Spitze (2130m). From there, partly pathless into the Schwarzwassertal, down to the Lech and along the river to Weißenbach am Lech. Via the old Gaichtpass road and the hiking trail back to Gaicht.
Length: 44,52 km
Altitude pos. 2970 HM / neg. 2970 HM (corrected)
--- german ---

This marvelous approx. 25k trail route runs along the coast of "Dänischer Wohld" (Danish Wohld) in Schleswig-Holstein, Germany. It is a point-to-point route from the gate of the lighthouse Bülk in Strande to the bus stop "Jordanschule", Kiekut in Eckernförde. It is 98% trail on the high coast, through small beach forest paths and includes 6k of running on the beach between Grönwohld and Lindhöft.

-submitted by Marc Müller