The center of the city is approx. 75 KMs from Santiago, depending on which route you take.
If you go by the main Duarte highway, it is a bit farther, but with faster moving traffic.
If you are on the West side of POP, then the Duarte highway would be the way to go.
If you are on the East side, then it would be quicker & shorter to go by the Caretera Turistica (tourist road) Gregorio luperon.