Camping at the primitive hiker-biker campsites along the C & O Canal NHP is free of charge and available on a first-come, first-serve basis. The Drive-In and Drive-In/Walk-In campsites charge a fee and now require advance reservations, which can be made at www.recreation.gov. Reservations are also required for the group campsite at Marsden Tract. One family or camping unit is allowed for each site. The park defines family as one head of household and immediate family. A camping unit consists of a non-family group of up to eight people.