There is no one currently signed route between the northwestern and southeastern points of Pennsylvania, but at one time there had been. When US 120 was first signed in 1926, it stretched from Erie to Philadelphia. The path it followed between Erie and Williamsport was:
In the City of Williamsport, it followed West Fourth Street, Water Street, Memorial Avenue, Cemetery Street, West Fourth Street, East Fourth Street, Mulberry Street, and East Third Street, before following SR 3014 to Montoursville where it was signed along Broad Street. After Montoursville, it followed:
In Reading it followed Centre Avenue, Fifth Avenue, Franklin Street, and Perkiomen Avenue before picking up current US 422 to Douglassville. There it left the US 422 alignment on High Street in Pottstown, Ridge Pike, then Main Street and Airy Street in Norristown before leaving on Germantown Pike then Germantown Avenue to end at US 309 in Chestnut Hill. In 1927, the route was under construction between Columbus and John Pondell Corners and between Sinnamahoning and Keating. From Keating to Shintown and North Bend to Lock Haven was still dirt, with the latter section not even open to traffic.
In 1928, the western terminus was moved to Ridgway and the eastern to Reading. That year construction to upgrade the route began from Clinton County line to Shintown, Hyner to Lock Haven, and the summit of Little Mountain to Shamokin, while work winded down from Sinnamahoning to the Clinton County line and North Bend to Hyner. In 1929, the route was completed from Bucktail State Park to Keating and from the summit of Little Mountain to Shamokin.
In 1930, the remaining sections from the Clinton County line to Bucktail State Park, Keating to Shintown, and Hyner to Lock Haven were paved. In 1935, the eastern terminus was moved for the final time from Reading to Lock Haven.
The route changed very little for the remainder of its existence, which finally came to an end in 1967.
Terminus of US 120 - Dale Sanderson
|US 219 in Ridgway.|
|US 220 in Lock Haven.|
Depot Street, Front Street, Saint Marys Road, Ridgway Road, State Street, General Edward Meyer Boulevard, Saint Michaels Street, Brusselles Street, Truman Road, Fourth Street, Allegheny Avenue, Huron Avenue, Renovo Road, Susquehanna Avenue, Water Street, Jay Street, and Paul Black Boulevard
|Counties:||Elk, Cameron, and Clinton|
|PA 55 (1927 - 1928)|
|Replaced By:||PA 120|