This article is about the Class III road numbered C637 maintained by DfI Roads. For other roads numbered C637, see C637.
The C637 forms a T-shaped route in east Tyrone. The road starts on the B43 south east of Donaghmore and heads north, soon meeting the C636 at a crossroads. Eventually the road comes to a halt at a T junction and continues both east and west of here. To the west the road follows a mostly straight path north west as it reaches the B160 at a fork to the east of Pomeroy. To the east the road crosses the A29 and terminates on the C638 at the north end of Newmills.