It roughly followed the Susquehanna Trail to Northumberland, US 11 to Shamokin Dam, US 15 to York Springs, and PA 94 to Maryland.

It runs through Roaring Branch before entering Bradford County.

PA 14 then runs through Snedekerville, Gillett, and Fassett before crossing the New York state line and becoming NY 14.

As in previous years, PA 14 remained concurrent with the roadway now carrying US 15 to Northumberland.

From Northumberland south to Duncannon, PA 14 was realigned onto the western bank of the Susquehanna River, creating an overlap with US 11.

[7][8] In 1941, PA 14 was rerouted to the east side of the Susquehanna River from Muncy to Clarks Ferry on what is now Interstate 180 and PA 147; the US 15 designation was moved west to run concurrent with US 11.