Minn. Stat. § 370.15: WHEN HIGHWAY CENTERLINE TO BE CITY AND COUNTY BOUNDARY.

Where a city of the fourth class in one county adjoins a city of the first class in another county, and the centerline of a highway running along the boundary line between these cities and counties deviates from the boundary line between these cities and counties, but the boundary line is within or on the lateral limits of the highway, then the centerline of the highway shall be established as the boundary line between the cities and the counties.