In 1940, the section between Highland Road and Bridge Road was paved.

In 1940, the section from Swede Hill Road to Maple Hill Road was paved.

In 1941, the section between Jackson Center and Perrine Corners was paved.

In 1940, the section from Game School Road to PA 949 was paved.

In 1938, the section from Morgan Run to Old Erie Pike was paved and from there to Twoey Run Road was improved.  The following year that section was paved.

The southern terminus was moved from US 322 east of Woodland to PA 350 in Sandy Ridge in 1946.

In 1968, the route was moved from US 322 onto its own alignment between Bigler and Woodland.

PA 970 used to follow a routing from US 322 to Woodland, through Pine Top, south past Bigler, and met its current routing west of Wallaceton without joining with US 322 to form a multiplex.  In 2002, the designation was moved to follow SR 2034 to multiplex with US 322 from Wallaceton to Woodland to continue north.

In 2005, the southern terminus was moved from Sandy Ridge to its current location.

Due to flooding caused by Topical Storm Lee on September 8, 2011, part of the western end of the Slabtown Bridge collapsed into the churning Loyalsock Creek.  Construction on a replacement span began soon after and was completed in November 2012 at a cost of $3 million.  The span was dedicated on September 10, 2013 as the "George E. Logue Sr. Memorial Bridge," named for a local resident who owned a construction company and patented several mechanical innovations.

In 1941, the section from US 19 to Boyce was improved.  In 1946, the route's southern terminus was moved to its current location from US 19 near the Washington County line.  In 1949, the route was paved between North Branch Road and Lutz Road.  In 1963, the route was paved between William Penn Highway and Imperial.

In 1962, the route was moved to Potato Garden Road, Washington Road, and Moon Clinton Road from another highway that is now under the airport facility.

In 1976, the northern terminus was moved from PA 51 at Narrows Run Road to its current location.  The former path followed Potato Garden Road, Washington Road, and Moon Clinton Road.

In 1951, the northern terminus was moved from US 30 in Clinton to the William Penn Highway.

In 1965, the northern terminus was moved to its current location from William Penn Highway to its current location.

The notoriously bad intersection at PA 50 had been an issue with Cecil Township officials, and remedies had been discussed since the mid-1990s; however, work to correct the problems finally began in February 2015.  A 90-foot-long railroad trestle, despised by truckers for its low clearance across PA 50, was demolished in 2001, but the rest of the work was cancelled due to insufficient funds.  The $2.3 million project realigned both approaches to PA 50 to remove the offset intersection and built a new bridge for bicyclists and pedestrians using the Montour Trail.  The project was completed in September 2015.

In 1940, the route between Old Cemetery Road and Locust Knob was paved, as was the future route between US 22 and Rushwood Road.

In 1952, the route was moved from Rushwood Road to its current alignment north of New Alexandria.  In 1954, the route was widened from Lloyd Avenue Extension to Latrobe.  In 1956, the route was moved onto the new interstate between PA 201 and PA 51.  In 1959, the southern terminus was moved from PA 201 at the Donora/ Monessen interchange of I-70 to its current location.

In 1959, construction began on a new four-lane, divided roadway between Depot Street and Ash Street Street in Latrobe.  Two years later the new alignment opened and with it, took the PA 981 designation from Latrobe-Derry Road between those two points.

In 1976, the route was changed in Mount Pleasant to its current route between PA 31 and PA 819.  Previously it had formed a multiplex with the latter from the intersection at PA 31 to PA 819 north of town.

In 1998, the route was extended to meet PA 819, which became its new northern terminus, near Salina from its former terminus at PA 156.

Beginning in 2000, PennDOT began studying improvements to the corridor from East Huntingdon Township to north of US 22.

Improving the route between Mount Pleasant and Latrobe began to gain traction in 2016 when the first open house was held in Norvelt on November 9 as part of the initial Feasibility Study phase.  The event was to showcase proposed improvements to the alignment between the PA 819 and US 30 intersections and gather public feedback on the proposals.  Plans were coming together by 2017 on how to correct the defects of the route which included a mix of improvements to the existing roadway and building new sections.  One such realignment will take place between Norvelt and the Westmoreland Airpark by upgrading SR 2023, known as Bell Memorial Church and Hill Churches roads, and bypassing to the east of Calumet, Trauger, and Pleasant Unity.  Not only are there less intersecting driveways, but it would eliminate difficult turns the current route of PA 981 takes through the latter village which trucks can not make.  About $68 million had been budgeted at the time for construction which was scheduled to begin in 2024 said Troy Pritts, project manager for PennDOT.

Another open house took place on January 29, 2020 at the Mount Pleasant High School to display the final design for the southernmost section, Section Q20.  "We’ve pretty much held to what we were hoping to do with the preferred alignment," Pritts said of the initial 4.5-mile segment.  Aside from smoothing out or bypassing curves, improvements include construction of roundabouts at the PA 819, Hecla Road/State Street, and Hecla Road/Mount Pleasant Road/Kecksburg Road intersections, widening the route's two lanes to 12-feet each, and building 8-foot-wide shoulders.  A completely new alignment would be built to the west from near Carpentertown Road to just south of the five-way intersection in Norvelt.  North of that junction, the alignment would shift to the northwest before rejoining the current route near Windy Hill Court.  This first section had received environmental clearances.  PennDOT expected to displace about seven residences, but more would have had to be taken without the jog to the west in the new route.  About $50 million had been set aside with construction projected to begin in spring 2021.  Before any work would start, an environmental survey looking for any geological or cultural resources that might impact construction was conducted in summer 2020.

PennDOT began to advertise for bids on July 29, 2021 with Walsh Construction Company's being accepted in late summer 2021 and were given notice to proceed on September 21, 2021.  A groundbreaking ceremony took place at the Little League field in Norvelt on November 12, 2021 to officially kick off work on the southern section.  Senate Majority Leader Kim Ward, said it is an example of the good things that can happen "when we all come together and work for the good of our communities.  Areas all over the state are fighting for projects, and we have a really good one here."  Speakers credited the efforts of past and present PennDOT officials, legislators, county commissioners and staff, and local leaders in moving the project forward.  "It’s a good recipe for success when everyone is pulling together," said Mike Keiser, PennDOT’s acting deputy secretary of highway administration.  "That’s really how things get done."  Bill Kovach, district executive for PennDOT District 12 said, "It’s a big investment in the community and the region," adding that the project is meant to "support current residents and also support future community growth and economic development."  Gabe Monzo, executive director of the Westmoreland County Airport Authority, which operates the Arnold Palmer Regional Airport in Latrobe, expressed his support for the project.  "That’s going to be the lifeblood of the airport moving forward," he said.  "It’s going to be the future of the southern connection for the airport.  It will make it much easier for people to get there."  The southern section is expected to cost $55 million and be finished by fall 2024.  Preliminary design is underway for the two remaining sections:  the central (Section V20) between Norvelt and PA 130 east of Pleasant Unity with an estimated cost between $35 million and $40 million and estimated not to begin before 2026, and the northern (Section Y10) between PA 130 and the Westmoreland Airpark with an estimated cost between $25 million and $30 million and estimated not to begin before 2025.

An additional $30 million for the Laurel Valley Transportation Improvement Project was received for the section between Norvelt and the Arnold Palmer Regional Airport, which was announced the week of December 6, 2021.  The influx of money came from the federal Surface Transportation Program according to Jay Ofsanik, PennDOT District 12 acting press officer.  This will allow the Department of Transportation to shift a similar amount of funding allocated for the northern section to the central section.  That earlier $30 million for the northern section was approved through the Southwestern Pennsylvania Commission and the state Transportation Improvement Plan.  "This now allows us to fully fund the entire project," Ofsanik said.  "It’s very good news.  Now we know we can continue to move forward on the two remaining sections."

This route holds a special place for me in that I grew up less than a mile from the roadway.

In 1936, the southern terminus was moved from the Borough of Livermore to PA 31 in Laurelville.  In 1938, the section from Weltytown to Lycippus was paved.

In 1946, the southern terminus was moved from Laurelville to US 119.

In 1951, the route became disconnected across the Conemaugh River.

In 1960, the northern terminus was moved from PA 680, currently PA 217 via Livermore Road in Westmoreland County and Grange Road in Indiana County to its current location.  This created a disjoined route between the two sides of the Conemaugh River.

Another route close to me since I spent the first three years of my life living just a few feet off of PA 982.  On a side note, the former bridge that carried PA 982 over the Loyalhanna Creek was featured in a Rolling Rock commercial in the late 1990s but was replaced in 2009.

Signed in 1980 in its current location.

From July 24 to July 28, 2002, the eyes of the world focused on the intersection of this route and Haupt Road near the southern terminus.  This was the location of the Quecreek Mine accident, and where the rescue effort unfolded. 

Signed in the current location in 1940.

A median was installed in 1954 at US 22.  In 1955, the southern terminus was moved from Union Avenue to the Lehigh Valley Thruway.

In 1940, the northern terminus was moved from PA 68 at Zeigler Road via Willoughby Run Road to its current location.  In 1941, the section from Phillips Street to Conway Wallrose Road was paved.

In 1941, it was widened in Trafford as well as the western terminus was moved from Trafford to US 30 in East Pittsburgh.  In 1947, the section between Harrison City and Business PA 66 was paved.  In 1948, it was moved onto Electric Avenue between Turtle Creek and Chalfant.

In 1976, the highway was truncated at its current location in Trafford.  Prior to that, its western terminus was at US 30 in Forest Hills after being multiplexed with PA 130 through the Turtle Creek Valley on the Tri-Boro Expressway and left PA 130 via Electric Avenue to US 30.

In 1964, the eastern terminus moved from PA 913 north of Robertsdale to its current location.

In 1941, the designation changed from the PA 316 alignment to its current route between Maryland and Waynesboro.  In 1947, the northern terminus was moved to PA 433 from PA 333 in the area now comprised of the Letterkenny Army Depot.

In 1964, the northern terminus was moved from Green Village to its current location.

In 1977, the route was moved from Mont Alto Road, Main Street, and Mount Pleasant Road, to its current route between Mont Alto and Smoketown.