County Trunk Highways (Wisconsin)
Standard Wisconsin county trunk highway shields
|Interstates:||Interstate X (I-X)|
|US Routes:||U.S. Highway X (US X)|
|State:||(State Trunk) Highway X (STH X or WIS X)|
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 US state of Wisconsin. Every county maintains its own County Trunk Highway system.
Wisconsin uses letters as route designations for its county roads. Routes may be labeled with a single letter (CTH-H), double letter (CTH-LL or CTH-AB) or triple letter (CTH-BBB). Roads are usually named sequentially, though there is leeway to have the letter designation stand for the initials of a road, geographical feature, or in honor of a person. 
Route designations may or may not be repeated within a single county, mostly depending on the size and population of the county. Designations also may or may not continue over a county line. Usually the letter designation remains the same when the route is a former Wisconsin state highway that has been decommissioned and turned over to county control.
County Trunk Highways first came into being in 1921. The first county highways were independent of the state's Trunk Highway System and lacked state legislative approval. By 1924, every county in Wisconsin had set up its own county highway system, with the state authorizing county highways in 1925.
- Bessert, Chris. "Wisconsin Highways: The Trunkline System". Wisconsin Highways. Retrieved 2007-03-20.