The Potawatomi Trail, in Pinckney State Recreation Area, is a 17.5 trail which is scenic, somewhat hilly and somewhat technical. It is open to mountain biking as well as hikers. Mountain bikers are encouraged to travel clockwise while hikers, counter clockwise. The trail does has several sub-routes where you can traverse shorter distances however the full trail is 17.5 miles.
A roughly 26 mile loop connecting several prominent trails in the Great Smoky Mountains National Park (Alum Cave, Boulevard) as well as parts of the Appalachian Trail. See link for description. https://www.hikingproject.com/trail/7026832/great-smoky-mountains-peak-loop.
Fawn Hernandez submitted this 17.7 mile route in Chicot State Park near Ville Platte, Louisiana:
"The most 'Louisiana' trail you will find - with long bridges through cypress swamps, hardwood forest and piney woods. Most of the trail is single track, and not as flat as you would suspect for south Louisiana."
This route has a Strava segment.
Alyssa is a “Professional Triathlete who can’t seem to shake her ultrarunning habit”. She has finished 30 Ironman Triathlons, 40 ultra races, and once finished 4th in the Taiwan Ironman using all borrowed gear. On July 31, 2018, she set a new women's FKT on Vermont’s 273 mile Long Trail of 5 days, 2 hours.
This unofficially named hill (around 65 vertical feet in about 0.2 miles) in East Dallas is used for hill training by local runners. Jonas Roos describes it as follows: