The highway leaves Pachuta and travels east through a mix of farmland and woodlands for several miles to become concurrent with MS 145 and they head north to cross the Chickasawhay River into Quitman. MS 18/MS 145 almost immediately enter downtown, with MS 18 splitting off at another junction with MS 512.
The highway departs Pachuta, traversing a mix of farmland and woodlands for several miles before merging with MS 145. It then heads north to cross the Chickasawhay River in Quitman.  MS 18/MS 145 quickly enters downtown, with MS 18 branching off at another junction with MS 512.