SR 187 begins at an intersection with SR 658 in the village of Guilford. The state highway heads east as two-lane undivided Guilford Road tothe town of Bloxom. SR 187 veers north along Shore Main Drive, then heads east again to intersect the northern end of SR 316 and cross an inactiverailroad line. The state highway curves north again, then veers east and follows Nelsonia Road through Macedonia to Nelsonia, where the highway meets US 13. Before entering Modest Town, SR 187 reaches SR 679 a short distance southwest of the community. SR 187 turns left onto Metompkin Road and passes through Modest Town before the designation ends just northeast of the community. SR 679 continues north as Metompkin Road.