Route 6 is a 211-mile-long (340 km) state highway in the northern part of the U.S. state of Missouri. It travels from I-29 Bus./US 169 in St. Joseph to US 24/US 61 about 6 miles (9.7 km) west of Quincy, Illinois. Route 6, if only a few miles longer in each direction, would be the only state highway to cross Missouri west to east. It is one of the original 1922 highways in Missouri.