The portion of the highway that runs through Mount Pleasant borough is said to have evolved from a Native American path that predated European settlers.

The route fully enters Lower Tyrone Township and heads into open agricultural areas with some trees and homes, turning east onto Dawson Scottdale Road and curving northeast again.

Here, the route passes through Tintsman and crosses under a Wheeling and Lake Erie Railway line, becoming Scottdale Dawson Road as it runs through areas of farms and woods with some residences.

[3][4] PA 819 crosses Jacobs Creek into East Huntingdon Township in Westmoreland County and turns north, running through farmland with some homes.

The road turns east and enters the borough of Scottdale, becoming South Broadway Street and heading northeast past homes.

The route curves northeast and heads into the borough of South Greensburg, running past more residences and turning west-northwest onto Reamer Avenue.

PA 819 comes to an intersection with US 119 and turns north to form a concurrency with that route on four-lane divided South Main Street, passing businesses.

Northbound US 119/PA 819 join eastbound PA 130 on one-way East Pittsburgh Street, carrying two travel lanes, before splitting to the north onto two-way Arch Avenue and rejoining southbound US 119/PA 819.

Past the one-way pair, both directions of US 119/PA 819 run northeast on two-lane undivided Arch Avenue, passing homes before curving north and crossing under Norfolk Southern's Pittsburgh Line.

The route heads between homes and woods to the west and fields to the east before passing through residential neighborhoods as it fully enters Greensburg again.

PA 819 crosses back into Hempfield Township and runs through a mix of farmland and woodland with some homes, turning northeast and passing through Forbes Road.

The road continues northwest through more woodland with some farms and homes, curving north into forested areas and becoming Stefaniak Drive.