From here, I-70 heads east to meet a weigh station and a welcome center in the eastbound direction, as well as an interchange with SR 3024 connecting to Pennsylvania Route 231 (PA 231) via US 40 in the borough of Claysville.

After passing through an interchange with Sheffield Avenue serving the industrial and commercial area of Jessop Place, the freeway enters the city limits of Washington, where it comes to a pair of right-in/right-out ramps that connect to PA 18.

A short distance later, I-70 enters South Strabane Township and reaches its western junction with I-79 at a directional interchange, which heads north toward the city of Pittsburgh.

Past PA 136, the freeway heads back into rural areas with scattered residences, before reaching the eastern split between I-70 and I-79 at a directional interchange.

[3] I-79 turns south toward the city of Morgantown, West Virginia, while I-70 continues east along the original roadway toward the borough of New Stanton in Westmoreland County.

Shortly afterward, the freeway crosses over Norfolk Southern Railway's Ellsworth Secondary and meets modified right-in/right-out ramps to Wilson Road, which provides complete access to PA 917 and the center of Bentleyville to and from both directions.

[3] Past PA 51, the route crosses the Smithton High-Level Bridge over the Youghiogheny River and CSX Transportation's Keystone Subdivision, where it enters South Huntingdon Township.

In this area, the freeway has an interchange with Waltz Mill Road to the south of the borough of Madison, before it passes through Hempfield Township prior to entering New Stanton.

I-70 itself passes through the toll plaza and comes to another trumpet interchange, where the Interstate merges onto the eastbound turnpike that heads toward the city of Harrisburg, the state capital of Pennsylvania.

The freeway continues through a valley of farmland and comes to an eastbound rest area on the western slope of Town Hill, which the highway crosses at an oblique angle.

In the middle of the mountain crossing, I-70 has another pair of right-in/right-out ramps with the northern terminus of PA 643, and then descends along the length of its eastern slope into another rural valley.

Within this valley, the freeway enters Union Township, turns generally more southeast and interchanges with the northern terminus of PA 731, east of the unincorporated village of Amaranth.

The route heads through forested and mountainous surroundings in the watershed of Tonoloway Creek, before coming to an interchange with the western end of the highway's concurrency with US 522 in the unincorporated town of Warfordsburg.

On February 26, 1964, as part of the formation of I-76 (east of Downtown Pittsburgh), the American Association of State Highway and Transportation Officials (AASHTO) approved a rerouting of I-70 along I-70S.

In 2011, the Pennsylvania Department of Transportation (PennDOT) began preliminary work for a total reconstruction of I-70 between the West Virginia state line and New Stanton.

Other planned improvements include six overpass replacements, a new roadbed, a wider median, electronic ITS signage, and widening the I-70/I-79 concurrency in Washington to six lanes.