continues along Perkiomen Avenue to St. Lawrence, where it intersects the western terminus of PA 562 and turns southeast.

In 1928, the US 120/PA 13 designation between Reading and Philadelphia was changed to US 422/PA 17 in order to provide for one number for the Benjamin Franklin Highway.

begins at an interchange with the US 222/US 422 freeway (Warren Street Bypass) in the borough of Wyomissing in Berks County.

After splitting from US 422, the route passes over Norfolk Southern's Harrisburg Line and crosses under US 222 (Warren Street Bypass), with interchange ramps providing access.

Past this interchange, the road continues northeast between the railroad tracks to the north and residential areas to the south.

heads further south from the railroad and continues past a mix of homes and businesses as a two-lane undivided road.

The route curves east and passes to the south of commercial development at the former Berkshire Knitting Mills.

passes more businesses, widening to a four-lane divided highway as it crosses under Norfolk Southern's Harrisburg Line #1 before reaching a cloverleaf interchange with the US 422 freeway (West Shore Bypass).

heads east, with the westbound direction passing north of the Berks County Courthouse, and crosses Norfolk Southern's Harrisburg Line #2 at-grade eastbound and on a bridge westbound, where the eastbound direction passes north of the former Franklin Street station at the railroad tracks before heading south of the BARTA Transportation Center serving BARTA buses.

Following this, the business route heads out of the downtown area, with the westbound direction of Washington Street becoming two lanes.

The one-way pair continues east through residential areas to the south of forested Mount Penn.

widens to a four-lane undivided road and passes over 19th Street on the Lindbergh Viaduct, at which point it becomes Howard Boulevard.

The one-way pair continues into the borough of Mount Penn and passes between Aulenbach Cemetery before Howard Boulevard heads southeast to join Perkiomen Avenue at the 23rd Street intersection in residential and commercial areas.

continues east on two-lane undivided Perkiomen Avenue past a mix of homes and businesses.

turns to the southeast and becomes a four-lane undivided road continuing through developed areas, crossing into Exeter Township.

[4] In 1916, the road between Reading and Harrisburg became a part of the William Penn Highway, an auto trail that ran from Pittsburgh to New York City.

In 1924, the William Penn Highway was designated as PA 3 with the establishment of the first state route numbers in Pennsylvania.

[9][10] In 1931, plans were made to reroute US 22 and the William Penn Highway to a more direct alignment between Harrisburg and Allentown by way of PA 43.

[12] In the 1950s, US 422/PA 73 was split into the one-way pair of Perkiomen Avenue eastbound and Mineral Spring Road westbound between Reading and Mount Penn.