County Trunk Highways (Wisconsin)
From Wikipedia, the free encyclopedia
County Trunk highways (also called County Highway, CTH, CR, or County Road) are a system of highways maintained at the county level or below in the U.S. state of Wisconsin. Wisconsin is unique in that the state uses only letters as route designations for their county roads. Missouri seems like it uses this method, however they are actually secondary state highways.
Each county maintains its own system. a particular county may have routes in single letter (CTH-H), double letter (CTH-LL or CTH-AB) or triple letter (CTH-BBB).[1]