Missouri State Route 231 runs breifly in Jefferson County. This runs from the St. Louis/Jefferson County Line, at the Meramec River to U.S. Rt. 61/67 in Arnold. MO St Rt 231 passes through the following town in Jefferson County. Arnold
MO St Rt 231 is not multi-plexed in Jefferson County. MO St Rt 231 intersects the following highways in Jefferson County. U.S. Rt. 61, at Arnold. U.S. Rt. 67, at Arnold.
SB MO St Rt 231 south of the St. Louis/Jefferson County Line. NB MO St Rt 231 north of U.S. Rt. 61/67. A junction marker on NB U.S. Rt. 61/67.
