Few people have crossed the country on the ADT on horseback and information is sparse.
The first page to read is the general FAQ
Are horses allowed on the ADT?
Horses are allowed on most of the ADT. A few examples of the places where they are prohibited include the eastern 12 miles of the C&O Canal into Washington, D.C.; the Knobstone Trail and Adventure Trail in Indiana; most of the Katy Trail in Missouri (only 20 miles between Sedalia and Calhoun are open to horses); and many of the rail-trails in Iowa. In addition, where the trail passes through urban areas, equestrians may find the going difficult. The ADT Society is working on alternative equestrian routes, but crossing the country via horseback is probably the most logistically challenging transportation mode.
Our most experienced horse rider is Samantha Szesciorka, firstname.lastname@example.org
Read about Matt Parker’s horseback crossing