This route starts at mile 0 - the Southern Most Point in the US in Key West and runs 100 miles to Key Largo (Mile Marker 100) and then returns to the Southern Most Point to cover a total of 200 miles over the scenic Oversees Highway. This run follows the old Flagler railway that connected Key West to the mainland Florida and is now part of the iconic Keys 100 race. Many have tried to complete this 200 journey but none have yet to succeed. 

Introduction

This open route traverses the state of Maryland from its lowest natural point (sea level) to its highest point atop Backbone Mountain: Hoye-Crest. Covering seven counties, this point-to-point effort links urban waterfront, suburban communities, rolling piedmont, vast farmland, and rugged Appalachian mountains.

The Route

This is an open route. The exact path is not prescribed, but the following rules must be met for an effort to be considered:

This is the winter-conditions variation of the standard Teton Crest Trail route, done on snow with ski equipment! Predominantly located above 8500ft, "winter" in this area is generally considered significantly later into the year than the spring equinox. It is a truly epic traverse across the length of the Teton range, and closely follows the summer running route. This variation is gaining in popularity and the existence of a proper record board is due.

Follows this historic canal, built during the industrial revolution, from its start in Birmingham, along 58 locks, to its end at the river Severn in Worcester. Mainly follows the towpath, with a few established diversion where the canal goes through tunnels. 

https://en.wikipedia.org/wiki/Worcester_and_Birmingham_Canal