Beginning off of GH-4 in Chalan Pago-Ordot, GH-15 proceeds eastward into Mangilao, where it intersects GH-10.

Towards the northern edge of Mangilao, GH-15 meets the southern end of GH-26, heading north towards Dededo.

GH-15 eventually crosses into Yigo and starts moving gradually inland.

Shortly after passing GH-15's most notable attraction, the Guam International Raceway, GH-15 makes its final major junction, with GH-29, a connector to GH-1 and the main gate to Andersen Air Force Base.

GH-15 finally continues north until it ends at Andersen AFB's rear gate.