Picket line
A picket line is a horizontal rope, along which horses are tied at intervals. The rope can be on the ground, at chest height, or overhead. The overhead form usually is called a high line.
A variant of a high line, used to tie a single horse, is a horizontal pole attached high on the side of a horse trailer. The attachment is designed so that the pole can be removed or folded against the trailer when not in use.
