In Shattuck, SH-15 splits off to the northeast, heading through Gage and Fargo, before ending in Woodward.

The eastern SH-15 picks up a US-64/412 south of Garber, and begins concurrent with State Highway 74 heading northbound.

It splits from SH-74 to head through Billings and has an interchange with Interstate 35 at milemarker 203.

After leaving US-77, it passes through Red Rock, and has a 4 miles (6.4 km)[3] concurrency with US-177, and splits off just north of the intersection with the Cimarron Turnpike.

It bridges Sooner Lake and runs for 15 more miles (24 more km) before ending at State Highway 18 north of Pawnee.