Pennsylvania Turnpike-First Section -Irwin to Carlisle, Pennsylvania - Engineering Landmarks on Waymarking.com

The Pennsylvania Turnpike, the first section, Carlisle to Irwin 160 miles. Ground Broken October 27, 1938 - Opened October 1, 1940. Was designated a National Engineering Landmark 1990. The recognition plaque is posted in the Sidling Hill Travel Plaza.

From Wikipedia: "After the Irwin interchange, the Pennsylvania Turnpike widens to six lanes and heads into the rural area west of Greensburg. Curving southeast, it reaches New Stanton; an interchange provides access to I-70, US 119 and the southern terminus of PA 66 (the Amos K. Hutchinson Bypass). The road narrows back to four lanes at this interchange, and I-70 forms a concurrency with I-76 on the turnpike. After New Stanton, the road passes over the Southwest Pennsylvania Railroad's Radebaugh Subdivision line and winds southeast to the exit for PA 31 in Donegal, which also provides access to PA 711. Continuing east past Donegal, the turnpike crosses Laurel Hill into Somerset County.

In this county, the road continues southeast to Somerset and an interchange with PA 601 accessing US 219 and Johnstown before it crosses over CSX's S&C Subdivision rail line. East of Somerset the highway passes north of the Somerset Wind Farm before it reaches Allegheny Mountain, going under the mountain in the Allegheny Mountain Tunnel.] Exiting the tunnel, the turnpike winds down the mountain at a three-percent grade, which is the steepest grade on the turnpike, and heads into Bedford County, passing through a valley. At Bedford, an exit for US 220 Business (US 220 Bus.) provides access to US 220 and the southern terminus of I-99; this exit also serves Altoona to the north.

East of Bedford the turnpike passes through the Bedford Narrows, a gap in Evitts Mountain. The turnpike, US 30, and the Raystown Branch of the Juniata River all pass through the 650-foot-wide (200 m) narrows. The road winds through a valley south of the river, before traversing Clear Ridge Cut near Everett. Further east, at Breezewood, I-70 leaves the turnpike.

After Breezewood, I-76 continues along the turnpike, heading northeast across Rays Hill into Fulton County. The turnpike continues east across Sideling Hill, before reaching an interchange with US 522 in Fort Littleton. After this interchange the highway parallels US 522 before curving east into Huntingdon County. The turnpike goes under Tuscarora Mountain through the Tuscarora Mountain Tunnel, entering Franklin County.] It then curves northeast into a valley to the exit for PA 75 in Willow Hill.

Again heading east, the road passes under Kittatinny Mountain through the Kittatinny Mountain Tunnel. Shortly after exiting the tunnel, the highway enters the Blue Mountain Tunnel under Blue Mountain. Leaving that tunnel, the turnpike heads northeast along the base of Blue Mountain to an exit for PA 997. East of this interchange the road enters Cumberland County, heading east through the Cumberland Valley on a stretch known as "the straightaway". Further east, the turnpike reaches Carlisle and an interchange with US 11 providing access to I-81. '