36 C.F.R. § 51.40
What are some factors to be considered in determining that outfitter and guide operations are conducted in the backcountry?
Determinations as to whether outfitter and guide operations are conducted in the backcountry of a park area will be made on a park-by-park basis, taking into account the park area's particular geographic circumstances. Factors that generally may indicate that outfitter and guide operations are conducted in the backcountry of a park area include, without limitation, the fact that:
(a) The operations occur in areas remote from roads and developed areas;
(b) The operations are conducted within a designated natural area of a park area;
(c) The operations occur in areas where search and rescue support is not readily available; and
(d) All or a substantial portion of the operations occur in designated or proposed wilderness areas.