Upon crossing Lehigh Gap in Blue Mountain, PA 248 enters Northampton County and becomes a two-lane undivided highway that heads southeast through rural areas, serving Bath and Nazareth.

From here, the route runs southeast through suburban areas to Wilson, where it turns east and follows city streets through Easton.

In 1961, PA 29/PA 45 was upgraded to a divided highway, with the portion between Bowmanstown and Lehigh Gap built as a freeway.

PA 248 begins at an intersection with US 209 near the borough of Weissport in Carbon County, where the road continues north as Canal Street.

After this, the route heads southeast and crosses the Pohopoco Creek, at which point it enters Lower Towamensing Township and curves south through forested areas parallel to the Lehigh River and the Norfolk Southern railroad tracks.

[3][4] The route becomes a freeway and heads southeast through wooded areas between Mauch Chunk Road and the Norfolk Southern line to the northeast and the Lehigh River to the southwest, crossing into the borough of Palmerton.

PA 248 heads into Moore Township and continues through rural land as Pheasant Drive, crossing the Hokendauqua Creek and passing through Beersville before curving southeast at Dannersville.

The route passes to the north of Penn-Dixie Pond before it continues through agricultural areas with some residential and commercial development.

The road runs between a couple warehouses and businesses to the northeast and farms and homes to the southwest before it widens into a four-lane divided highway and reaches an interchange with the PA 33 freeway.

The route becomes a divided highway and heads into commercial areas, where it reaches an interchange with the westbound lanes of the US 22 freeway.

PA 248 turns east onto Pearl Street and runs between the Bushkill Creek to the north and neighborhoods to the south, passing through wooded areas.

Past this intersection, Larry Holmes Drive continues south as part of PA 611 parallel to the Delaware River.

[6] With the creation of the U.S. Highway System in 1926, the road between Weissport and Lehigh Gap was designated as part of US 309, a route that ran from Philadelphia north to Wilkes-Barre.

[11] By 1930, a portion of PA 45 northwest of Bath was paved, with the section between Lehigh Gap and east of Walnutport under construction.

[15][16] In 1961, PA 29/PA 45 was upgraded to a divided highway between Weissport and Lehigh Gap, with the portion south of Bowmanstown constructed as a freeway.

[2][19][20] On November 24, 1998, an act of the Pennsylvania General Assembly designated the portion of PA 248 in Carbon County as the POW/MIA Remembrance Highway in honor of soldiers who are prisoner of war (POW) or missing in action (MIA).