After heading northwest out of the mountains, the route continues into the agricultural Cumberland Valley, where it intersects Interstate 81 (I-81) and US 11 and crosses PA 641 in Newville.

The route heads entirely into Quincy Township as it passes the Penn State Mont Alto university campus.

PA 233 curves east before heading northeast through more forests and entering Guilford Township again, where it crosses the Appalachian Trail.

At this point, the route runs between East Big Flat Ridge to the northwest and Piney Mountain to the southeast, paralleling Conococheague Creek.

PA 233 curves north again and crosses into Penn Township, passing through more dense forests before heading north-northwest into open agricultural areas with a few homes, running through South Fairview.

The road crosses Norfolk Southern's Lurgan Branch railroad line and Yellow Breeches Creek prior to running through more farmland with some woods and residences, reaching a junction with PA 174 in Dickinson.

[2][5] At this point, the road crosses into West Pennsboro Township and passes through more agricultural areas with occasional patches of woodland and residences.

The route heads into North Newton Township and becomes Doubling Gap Road, running through farmland and woodland with some homes.

PA 233 crosses the Conodoguinet Creek into Lower Mifflin Township and curves north through more agricultural areas, coming to a bridge over I-76 (Pennsylvania Turnpike).

The road crosses back into Tyrone Township and becomes unnamed, heading north through farmland with some homes.

The route turns north into open agricultural areas with some homes, reaching its northern terminus at PA 274 in Green Park.

Upon designation, the route was paved between Dickinson and south of Doubling Gap while the remainder north to Dromgold was unpaved.