South Dakota

https://tophorsetrails.com/trails/SD/5728-3-Ponds-Trail-
7.6 mile loop trail.

https://gfp.sd.gov/parks/detail/bear-butte-state-park/
Northernmost point of 111 mile Centennial Trail
2.5 mile Lake trail.
4 non-electric horse campsites.

https://www.alltrails.com/explore/trail/us/south-dakota/bear-gulch-trail–2
Custer State Park.
8.4 mile loop multi-use trail.

https://gfp.sd.gov/parks/detail/big-sioux-recreation-area/
2.8 mile multi-use Prairie Vista trail.

7.7 mile multi-use trail.

Custer State Park / Trail access fee.
7.1 mile multi-use trail.

https://www.fs.usda.gov/activity/blackhills/recreation/horseriding-camping/?recid=25823&actid=104
An overview of multiple trail system details:
Centennial Trail – Trail #89
Big Hill Trail, Trail #72
Sundance Trail, Trail #93
Willow Creek Horse Camp, Trail #8
Iron Creek, Trail #5
Black Elk Wilderness, Trail #89

https://www.tophorsetrails.com/trails/SD/3143-blue-diamond-and-woodland-trail-loop
Newton Hills State Park.
4.6 mile out & back multi-use trail.

Custer State Park.
4.3 mile out & back multi-use trail.

Midway Recreation Area, 3.7 mile multi-use trail.
Chalk Bluffs, 4.1 mile multi-use trail.
8 equestrian campgrounds.

https://gfp.sd.gov/csp-trails/
22 mile Centennial Trail.
9 hour ride, French Creek & Mt. Coolidge Trail.
4 hour ride, Big Tree & Robbers Roost Draw Trail.
4 hour ride, Parker Canyon Trail.
5 hour ride, Racetrack Butte & Buffalo Corrals.

https://www.fs.usda.gov/recarea/blackhills/recreation/horseriding-camping/recarea/?recid=80633&actid=104
Black Hills National Forest.
12.8 mile Centennial multi-use trail. (North)
6.1 mile Centennial multi-use trail. (South).

https://www.fs.usda.gov/recarea/blackhills/recreation/horseriding-camping/recarea/?recid=82050&actid=104
100 mile multi-use trail system.

Custer State Park.
12.8 mile multi-use trail.

https://gfp.sd.gov/parks/detail/george-s–mickelson-trail/
109 mile trail, with 15 trailheads.

Black Elk Wilderness Area.
13 mile multi-use trail.

https://www.hikingproject.com/trail/7083355/horsethief-lake-loop
Black Elk Wilderness Area.
11 mile multi-use trail.

Black Hills National Forest.
4.6 mile multi-use trail.

https://gfp.sd.gov/parks/detail/lewis-and-clark-recreation-area/
4.1 mile horse trail.
Horse camp.

https://tophorsetrails.com/trails/SD/4821-lost-cabin-trail
Black Hills National Forest.
14.7 mile loop trail.

https://gfp.sd.gov/parks/detail/newton-hills-state-park/
Fee required for all over 11 years old.
6 mile Blue Diamond multi-use trail.
10 horse campsites.

https://gfp.sd.gov/parks/detail/oakwood-lakes-state-park/
2.5 mile Oakwood Lakes Prairie Trail.
6 horse campsites.

https://www.blackhillsbadlands.com/trails/bhnf-trail-58-osprey-trail/
Black Hills National Forest trail #58.
2.2 mile trail.

https://www.bivy.com/adventures/us/south-dakota/palmer-creek-trail-harney-peak-5890174135304192
2.9 mile multi-use trail.

https://gfp.sd.gov/parks/detail/pease-creek-recreation-area/
3.5 mile multi-use trail.
5 horse campsites (fees).

https://gfp.sd.gov/parks/detail/pelican-lake-recreation-area/
5 mile multi-use natural trail.
6 horse campsites.

https://gfp.sd.gov/parks/detail/richmond-lake-recreation-area/
3 mile multi-use natural trail.

https://gfp.sd.gov/parks/detail/sheps-canyon-recreation-area/
Fee required for all over 11 years old.
5.1 mile Red horse trail.
0.69 mile Yellow horse trail.
11 horse campsites.

https://gfp.sd.gov/parks/detail/sica-hollow-state-park/
Fee required for all over 11 years old.
8 mile horse trail.
8 horse campsites.

https://gfp.sd.gov/horseback/
General source of South Dakota horse trail information.

https://gfp.sd.gov/parks/detail/union-grove-state-park/
4.3 mile Mosey Meadow multi-use trail.
4 horse campsites.