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Total Reconstruction and Widening of MP 40 to 48
Archaeological Investigations

SurveyIn 2013, the Pennsylvania Turnpike Commission (PTC) began a major construction project called the Milepost 40-48 Total Reconstruction & Widening Project to widen eight miles of the Turnpike in Allegheny County between the Butler Valley Interchange (Exit 39) and Allegheny Valley Interchange (Exit 48).
View photos from the investigation!

About the Archaeological Investigations

The PTC completed a Phase I survey, which is a general survey of the area to determine if the project would possibly damage or negatively impact historic resources. Archaeologists reviewed historic records and conducted site investigations to document the presence of artifacts and/or historical significance. The Phase I survey found 12 archaeological sites, of which five were determined to be significant enough to conduct a Phase II Survey, which is a more detailed investigation. The Phase II Survey determined that the Armstrong Site was significant enough to list on the National Register of Historic Places. As the site was slated to be adversely impacted as part of the project, federal permits triggered a review under Section 106 of the National Historic Preservation Act, which requires agencies to take into consideration the effect of a proposed project on historic properties or sites. To preserve important information, the PTC completed a Phase III Archaeological Data Recovery effort that included the excavation and formal documentation of the entire Armstrong Site.

Outreach and Education

As part of mitigation for impacting the site, the PTC and PA State Historic Preservation Office (PA SHPO) agreed to develop an informational brochure to share the history of the Armstrong Site and the outcome of the excavations. In addition, we are conducting an online survey to evaluate the effectiveness of a printed brochure versus online communication. To participate in the survey, please visit:

About the Armstrong Site (36AL629)Brochure link

The Armstrong Site is named for the Armstrong family who lived in the area over 150 years ago. In 1875, John Armstrong sold his land to Adam, Robert, Samuel and John Seibert for $5,000. The records show that the property had a house and a stable. The historic research suggests that John Armstrong did not live on the land very long and it is most likely that the artifacts came from the Siebert family. The 1880 agricultural census indicates that John Seibert and his family were farmers who raised livestock and planted crops for market. Over 28,500 artifacts found at the site such as broken ceramic pieces of plates, bowls, and cups and pieces of glass bottles provide a glimpse into the daily lives of late 19th and early 20th-century farming families. Items such as brick pieces, nails and window glass from the homestead paint a picture of what the farm looked like.

Why are archaeology investigations undertaken?Cabin

Federal law requires that any project requiring federal action must consider how it might affect historic properties. The Milepost 40-48 Total Reconstruction & Widening Project needed permits from a federal agency, the Army Corps of Engineers (ACOE), which triggered the Section 106 process. The PTC and ACOE worked with the State Historic Preservation Office and other groups to conduct the appropriate research and archaeology surveys. See the Citizen's Guide to Section 106 Review to learn more about this process.

For more information about archaeology and history in Pennsylvania, we suggest visiting the following sites:
PA State Historic Preservation Office
Depreciation Lands Museum
Heinz History Center & The Historical Society of Western Pennsylvania
Heinz History Center- Western Pennsylvania History Magazine
Society for Pennsylvania Archaeology