In 1946, the western terminus was moved from PA 18 in Mechanicsburg to US 30.  In 1976, the designation was extended across Laurel Road to the new location at PA 51 along the Ohio River.

In 1946, the northern terminus was moved from PA 113 in Silverdale to US 309 at Stenton Avenue in Sellersville.  In 1954, the southern terminus was moved from Broad Street via Stenton Avenue and Ogontz Avenue to US 309 at Stenton Avenue, then again in 1960 from there to its current location.

In 1946, the section from Old Erie Pike and Dimeling Road was paved.  In 1949, the section from Bucket Line Road to Old Erie Pike was paved.

A median was installed in 1967 from US 322 to Clearfield.  In 1968, the southern terminus was moved from Munson to Clearfield.  The northern terminus moved from Penfield to US 219 in 1962.  The Southern terminus moved to Houtzdale from Clearfield in 1971, and then to its current location in 1995.

Signed in 1936 on the current alignment.  In 1938, the section from Columbia County line to Emmons was improved.  In 1946, the southern terminus was moved to its current location from Coles Creek.

In 1930, the route from Shanksville to Boone was paved.  In 1932, the route from Brotherton to Shanksville was paved.  In 1936, the northern terminus was moved from Windber to Ebensburg.  In 1947, the southern terminus was moved from PA 31 in Brotherton via Shanksville to its current location.

The route was moved to the current alignment between Salix and Wilmore in 1966, from Peaceful Valley Road, Dunlo Dip Road, and Washington Avenue.  In 1968, the designation was moved off Wilmore Road to its current route into Ebensburg.

In 1936, the western terminus was moved to Portage from Leamersburg while the eastern terminus was moved from US 30 to its current location.  In 1959, the western terminus was moved to Munster.

Until 1972, the designation was signed on Johnstown Road between East Freedom and McKee.  That year it was moved to its current routing.

In 1932, the section from US 119 to New Geneva was paved.  In 1938, the section between New Geneva and Gallatin was paved.  In 1946, the northern terminus was moved from Masontown to its current location.

For some reason, he route was not extended northward to intersect the new US 40 alignment when it opened on December 5, 2007.

In 1936, the northern terminus was moved from Montrose to the New York state line.  In 1938, the section from Turnpike Road to the Bridgewater Township line was paved.  In 1940, the section from the Brooklyn Township line to Tiffany was paved.

In 1931, the section from Ohioville to Esther was under construction and opened the following year, when the section from Esther to Union Road was paved.  Also, the section from Frankfort Springs to US 30 was paved.  In 1936, the northern terminus was moved from Beaver to Leesburg.

In 1940, the route between Darlington and Moravia became completely paved.  Also, between PA 251 and Darlington was improved as was the section between Moravia and East Moravia.  In 1946, the route was paved from PA 251 to Darlington.  Also, the designation was moved from Smith Ferry Road between PA 68 and Ohioville to its current alignment.

In 1951, the route was changed from Hookstown to Georgetown to its current alignment between Hookstown and Shippingport.  In 1964, the bridge between Shippingport and Midland opened replacing a ferry.

Signed in the current location in 1961.

Signed in from 1929 to 1938 on Dewitt Camp Road in Union County.

In 1938, the route was moved to its current location.  In 1963, the western terminus was moved to Shippensburg from Mooredale.

Signed in the current location in 1961.

Signed on its current alignment in 1961.  A median was installed in 2003 from US 30 to Interstate 83.

Signed in the current location in 1961.

Resigned in 1961.  The southern terminus was moved from PA 23 west of Phoenixville to its current location in 1962.  That year it was signed on its current alignment in Reading from Schuylkill Avenue, Fourth Street (northbound), Washington Street (northbound), Chestnut Street (northbound), Ninth Street, Second Street (southbound), Franklin Street (southbound).  A median was installed in 1963 at the Berks/Schuylkill County line.

In 1989, the route was placed on its current alignment between Campbell Road and Edwards Road when that segment was completed.

Signed in the current location in 1961, with the southern terminus in Center Valley.  In 1974, the southern terminus was moved from PA 309 in Center Valley to its current location.  It used to travel through Bethlehem on Wyandotte Street, Main Street (northbound), Elizabeth Avenue, and Center Street, with southbound traffic using Linden Street, Union Boulevard to the PA 378 expressway.

Signed on its current alignment in 1961.