U.S. Federal Route 12 runs mostly north-south in Jackson County. It runs from the Monroe/Jackson County Line, near Warrens, to the Clark/Jackson County Line, near Humbird. This runs through the Black River State Forest. U.S. Rt. 12 passes through the Jackson County. Millston Black River Falls Merrillan U.S. Rt. 12 is multi-plexed in Jackson County. Wisconsin State Route 27, from Black River Falls to the Clark/Jackson County Line.