In Kenosha County, there is no official legal date — or ordinance, anywhere in the state — that decrees when the trails open. It is up to the local county, clubs, etc., as to when they are marked and ready. Then, they will open.
Obviously, it differs in different parts of the state, depending on their local snow conditions and their progress in completing the trail marking/preparation.
For the most up-to-date information on trail conditions in Kenosha County, call the hotline at 262-671-4944.
Also see Are the Trails Open Yet? for more information.