Highways are left unsigned for a variety of reasons, and examples are found throughout the world.
Depending on the policy of the agency that maintains the highway, and the reason for not signing the route, the route may instead be signed a different designation from its actual number, with small inventory markers for internal use, or with nothing at all.
Several highway maintenance agencies have multiple numbering systems for the different classes of routes they maintain (freeways, expressways, rural roads, etc.).
In such cases, one or more class of numbers may be reserved for minor routes and these may or may not be signed.
There are several instances where a route has officially been given a name by government agencies, and is signed with that name, but the route is also assigned a number by the highway maintenance agencies as to fit in their maintenance and inventory systems.