Wis. Stat. § 349.065: Uniform traffic control devices.

Local authorities shall place and maintain traffic control devices upon highways under their jurisdiction to regulate, warn, guide or inform traffic. The design, installation and operation or use of new traffic control devices placed and maintained by local authorities after the adoption of the uniform traffic control devices manual under s. 84.02 (4) (e) shall conform to the manual. After January 1, 1977, all traffic control devices placed and maintained by local authorities shall conform to the manual.