Dajabón is at to the northwest of Santo Domingo, on the western end of the "Yaque del Norte Valley" (or "Línea Noroeste"), a part of the larger "Cibao" valley. The city is on the eastern side of the Dajabón or Masacre river; this is the only important river in the municipality. There is a bridge across the river and the Haitian city of Ouanaminthe is near the western side of the river.