This article is about the Class III road numbered C604 maintained by DfI Roads. For other roads numbered C604, see C604.
The C604 forms a collection of roads to the east of Strabane, totalling over 26km in length. The road starts on the B48 at Aghabrack and heads initially south west before it reaches a T junction and TOTSOs north west. The road meanders round corners and up and down hills as it comes to a T junction just after crossing the Dunnyboe Burn. At the T junction one segment of the route continues ahead to the north west while the other turns off westwards to the left. The route ahead soon splits again with one road leading to the B48 in Donamena and the other leading to the B49 west of Donemana. The road to the west continues as far as the approach to Artigarvan with a spur turning off to the north into the village where it meets the B49. The main line of the C604 continues west for a short distance before it TOTSOs south. After a couple of sharp turns the road heads in a generally westerly direction while gradually swinging round to the south towards Strabane. The road encounters another TOTSO on the terminus of the C605 on the way into Strabane along Curlyhill Road and Church Street. The final section of Church Street between Patrick Street and the B72 in the town centre is eastbound only with westbound traffic having to use Patrick Street in order to reach the B72.