Michigan State Route 51 runs north-south through southeastern Berrien County. This connects Niles to South Bend, IN, via IN St Rt 933. MI St Rt 51 passes through the following town in Berrien County. Niles
MI St Rt 51 is multi-plexed in Berrien County. BUSN. U.S. Rt. 12, at Niles.
Junction marker on EB BUSN. U.S. Rt. 12 in Niles. EB BUSN. U.S. Rt. 12/SB MI St. Rt. 51 at U.S. Rt. 12 on the southside of Niles. Guild marker on SB MI St Rt 51 south of Niles. SB MI St Rt 51 south of Niles.