Its western terminus is on the east bank of Pine Creek at PA 44 in the unincorporated village of Tomb (or Tombs Run) in Watson Township, and its eastern terminus is at the hamlet of Loyalsockville in Upper Fairfield Township at PA 87.

It then heads east into Mifflin Township, following Mud Run and the First Fork of Larrys Creek before crossing Larrys Creek and PA 287, and turning north into the borough of Salladasburg.

There PA 973 follows Hoaglands Run east through the village of Quiggleville and hamlet of Perryville, passing a single offramp from southbound I-99/US 15 and overpasses carrying I-99/US 15 before crossing Lycoming Creek into Hepburn Township.

Following Lycoming Creek southeast, PA 973 passes through the villages of Cogan Station and Hepburnville, then turns northeast to follow Mill Creek to the hamlet of Balls Mills, and on into Eldred Township.

Heavy rain from the remnants of Tropical Storm Lee raised the creek "higher than anything we've seen in recorded history", according to a Lycoming County official.