Wis. Stat. § 83.15: Aid by county for state line bridge or highway.

The county board of any county bounded in part by a river, or by a highway, either of which is also a state boundary line may aid any municipality of such county in the construction of a bridge across such river or any part thereof, or in the reconstruction of the highway including its bridges by an appropriation therefor not exceeding one-third of the cost of such bridge or of such highway.