Franklin and Adams counties

PA 233 northbound past US 30 in Greene Township

PA 233 begins at an intersection with PA 997 in the borough of Mont Alto in Franklin County, heading east on two-lane undivided Park Street. The road passes homes, becoming the border between Quincy Township to the north and Mont Alto to the south before fully entering Mont Alto again. The route heads entirely into Quincy Township as it passes the Penn State Mont Alto university campus. From here, PA 233 becomes Rocky Mountain Road South and continues near Mont Alto State Park and heads into Michaux State Forest. The route turns northeast to ascend Rocky Mountain, a part of the South Mountain range, becoming Rocky Mountain Road. The road enters Guilford Township and makes a hairpin turn to the south to descend the mountain, crossing back into Quincy Township. PA 233 curves east before heading northeast through more forests and entering Guilford Township again, where it crosses the Appalachian Trail. The route turns north-northeast and runs through more mountainous areas, heading into Greene Township. Here, PA 233 passes through Caledonia and crosses US 30 before running through forested Caledonia State Park as Pine Grove Road, turning northeast.^[2][3]

PA 233 crosses into Franklin Township in Adams County, leaving Caledonia State Park and continuing northeast through more of Michaux State Forest on Pine Grove Road. At this point, the route runs between East Big Flat Ridge to the northwest and Piney Mountain to the southeast, paralleling Conococheague Creek. The road stops following the creek as it heads into Menallen Township, running through more areas of mountains.^[2][4]

Cumberland and Perry counties

PA 233 northbound in Tyrone Township

PA 233 heads into Cumberland County and becomes Centerville Road, briefly passing through Southampton Township and South Newton Township before continuing into Cooke Township. The road runs through more mountainous areas of Michaux State Forest, passing near Pine Grove Furnace State Park before reaching the community of Pine Grove Furnace, where it crosses the Appalachian Trail again. At this point, the route turns to the north and runs through more rural areas, turning northwest to leave the state forest and continue through more forested areas. 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. From here, the route turns northwest through more farm fields, reaching an interchange with I-81. A park and ride lot is located northwest of this interchange. Past this, PA 233 continues through more rural areas as it comes to an intersection with US 11.^[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 becomes the border between the borough of Newville to the west and West Pennsboro Township to the east before fully entering Newville at the crossing of the Big Spring Creek. Here, PA 233 becomes South High Street and passes homes, intersecting PA 533 prior to heading into the commercial downtown and crossing PA 641. Past this junction, the route becomes North High Street and passes more residences along with a few businesses. 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). From here, the road winds north through farmland with some woods and residences, turning to the northwest. Farther northwest, the route intersects the western terminus of PA 944 before reaching the northern terminus of PA 997 near McCrea. PA 233 curves north through into more wooded areas with some farms and homes. The road turns northeast and heads into forested areas at the base of Blue Mountain that are a part of the Tuscarora State Forest, passing near Colonel Denning State Park before ascending the mountain.^[2][5]

At the summit of Blue Mountain, PA 233 passes through Doubling Gap and crosses into Southwest Madison Township in Perry County, leaving the Tuscarora State Forest boundaries and descending the forested mountain as it continues northeast. The route heads into woodland with some farm fields and homes, heading into Tyrone Township. The road runs through more agricultural areas as it heads more to the east and crosses Shermans Creek. PA 233 passes homes and comes into the borough of Landisburg, reaching an intersection with PA 850. At this point, PA 233 turns northwest to form a concurrency with PA 850 on Carlisle Street, passing more residences. The road crosses back into Tyrone Township and becomes unnamed, heading north through farmland with some homes. PA 850 splits from PA 233 by heading to the northwest, and PA 233 continues northeast on Green Park Road, running through farms and woods with occasional residences. The route turns north into open agricultural areas with some homes, reaching its northern terminus at PA 274 in Green Park.^[2][6]