This map comes from the USFS Kaibab Forest, west of Flagstaff. They do a great job of mapping out the old history routes. If you like 'Route 66', they also have identified many of the old sections west of Flagstaff. Really good.

The Overland Trail originally cut south at Sunset Crossing (Winslow) and then south through Sunset Pass. However after the railroad arrived in Flagstaff, the route was moved further west, taking travelers from Flagstaff southwest to Prescott. With the later railroad from Seligman to Prescott (and later from Ashfork), the Overland route fell into general disuse. But, it's great to explore these days. This picture is just a copy of the USFS brochure.

Map from USFS; Kaibab Ranger District.