Missouri Secondary State Route J runs north-south in Western Callaway County. It runs from Interstate 70/U.S. Rt. 40/Missouri Secondary State Route DD, south into the Mark Twain National Forest to near New Bloomfield. MO Sec St Rt J passes through the following towns in Callaway County. Millersburg
A BGS on WB I-70/U.S. Rt. 40. A junction marker on EB MO Sec St Rt WW. SB MO Sec St Rt J at Millersburg. NB MO Sec St Rt J near MO Sec St Rt MM. NB MO Sec St Rt J in New Bloomfield. A BGS on NB U.S. Rt. 54.