Rare, printed maps must be stamped and source marked.
Bound, folded maps usually are best housed as issued (i.e., folded and enclosed in the board covers). Some may benefit from tissue backing to reinforce fold lines. Consult with the Preservation Coordination Librarian as necessary.
Unbound, folded maps may or may not be flattened and stored in oversize storage (including rolled), depending on condition, expected use, and artifactual value. However, sectioned maps mounted on linen usually can be stored folded in folders, housed and stored as originally intended.