text: mississippi highway 366 ( prentiss county ) mississippi highway 366 ( ms 366 ) is a highway in prentiss county , mississippi . it starts at ms 370 at the lee – prentiss county line in the west . the route intersects many county routes as it travels eastward to ms 371 , its eastern terminus . the route was designated in 1957 , and became fully paved by 1971 . route description ms 366 starts at ms 370 on the lee – prentiss county line . the route curves northward after intersecting county route 5011 ( co 5011 ) . at co , the road begins a series of turns through the forest . ms 366 soon reaches co and dips southeastward . it temporarily heads eastward at co , before turning south at co 5345 . the route travels east again at co , around a small area of farmland . ms 366 crosses over casey creek after intersecting co . the road shifts upward as it enters marietta , and ms 366 ends at ms 371 . the road continues on as co . in 2013 , mississippi department of transportation ( mdot ) calculated as many as 760 vehicles traveling west of co 5311 , and as few as 650 vehicles traveling east of co . ms 366 is not included as a part of the national highway system ( nhs ) , a network of highways identified as being most important for the economy , mobility and defense of the nation . it is legally defined in mississippi code § 65 - 3 - 3 . all of ms 366 is maintained by mdot . history ms 366 was designated in 1957 , as a gravel road from ms 370 to ms 363 . by 1965 , ms 363 and ms 371 were rerouted , causing ms 366 's eastern terminus to change to ms 371 . all of ms 366 was paved by 1971 . major intersections