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 starts its journey from Pachuta, passing through 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.