Wisconsin State Route 27 runs north-south in Eastern Jackson County. It goes from Monroe/Jackson County Line, near Shamrock, to the Clark/Jackson County Line, near Humbird. WI St Rt 27 passes through the following towns in Jackson County. Shamrock Black River Falls Merrillan WI St Rt 27 is multi-plexed in Jackson County. U.S. Rt. 12, from Black River Falls to the Clark/Jackson County Line.