North of the bridge that crosses the Allegheny River, PA 8 meets Pennsylvania Route 28 at an interchange.

8 miles (13 km) north of Pittsburgh, PA 8 intersects Interstate 76 and the Pennsylvania Turnpike at exit 39.

In Middlesex Township, PA 8 runs concurrent with Pennsylvania Route 228 for 2 miles (3 km).

About 3 miles (4.8 km) east of Slippery Rock, PA 8 meets Pennsylvania Route 108.

A few miles north of the Butler-Venango county line, PA 8 meets Interstate 80 at exit 29 near Barkeyville.

About 0.5 miles (0.8 km) north of the interchange of PA 28 (in the borough of Etna) is a very sharp and hazardous curve, known to Pittsburghers as "Mae West Bend".

The expressway, built between 1973-1976, is 9 miles (14 km) long and has only two exits, one of which serves as the northern terminus of Pennsylvania Route 308.

The routes form a short, 0.5 miles (0.8 km) concurrency through the city before splitting near the Allegheny River.

Just north of the split with US 6, PA 8 meets the southern terminus of the northern segment of Pennsylvania Route 97.

1.5 miles (2.4 km) southeast of Erie, PA 8 interchanges with Interstate 90 at exit 29, which shows a sign for Parade Street (northbound) and Hammett (southbound).

Later, in 1958, construction commenced on the segment from Grant Avenue to Pennsylvania Route 28 in Etna.

That same year, the southern terminus of PA 8 was moved from West Carson Street in Pittsburgh to Pennsylvania Route 28 in Etna.

In 1974, construction began on the remainder of the expressway from the present southern end at Wesley to PA 308.

In 1980, the designation was established to remove trucks from the complicated intersection with Pennsylvania Route 27 and to provide direct access for local trucks past the borough's small industrial area along St. John Street.