Potomac Heritage National Scenic Trail Permit

It depends which component you're on. There is no single Potomac Heritage Trail permit for the network as a whole. The C&O Canal towpath and the Mount Vernon Trail need nothing at all. The Laurel Highlands Hiking Trail is the exception: its overnight shelters and tent sites require a paid reservation through Pennsylvania's state park system.

The National Park Service's own figure is 'over 900 miles' across the whole braided network of component trails, not one continuous footpath.

The C&O Canal towpath (184.5 miles, Georgetown to Cumberland), the Mount Vernon Trail (17 miles), the Laurel Highlands Hiking Trail (70 miles, Ohiopyle to Seward, PA), a 73-mile designated portion of the Great Allegheny Passage, the 16-mile Dahlgren Railroad Heritage Trail, and the Civil War Defenses of Washington Trail.

Yes. Hiker-biker campsites along the towpath are first-come, first-served with no fee and no reservation, spaced roughly every 5 to 7 miles, though stays are limited to one night.

Yes. Its eight overnight shelter areas must be reserved in advance through Pennsylvania's state park system, at $4 a night for PA residents and $5 for non-residents, per person, per shelter or tent site.

It has two southern anchor points at the mouth of the Potomac River, Point Lookout in Maryland and Smith Point on Virginia's Northern Neck, and stretches to the northern end of the Laurel Highlands Hiking Trail in western Pennsylvania's Allegheny Highlands.

Yes. Several of its main components, including the C&O Canal towpath, the Mount Vernon Trail, and the Great Allegheny Passage section, are shared hiking-and-biking paths.