McConnell's Mill Covered Bridge
Why it's listed
Spanning Slippery Rock Creek in Slippery Rock Township, Lawrence County, this covered bridge was built in 1874. It carries a Howe truss, a timber framing system in which vertical posts and diagonal iron rods work together to bear the load. The structure measures 96.5 feet from end post to end post and 15 feet wide, with 10 feet of vertical clearance and a rated load of 5 tons. Its gable roof and vertical plank siding enclose the span, and it has no window openings. The nomination counts it among four surviving Pennsylvania covered bridges using the Howe truss, and the longest of those four. It is also one of only two covered bridges remaining in Lawrence County. Recorded as being in good condition, the bridge was listed as part of a county thematic group of covered bridges, which documents the regional survival of this type of construction.
Significance in brief: The bridge is one of four remaining covered bridges in Pennsylvania that use the Howe truss, and it is the longest of those four. The document also notes it is one of only two covered bridges remaining in Lawrence County, and that it is in good condition with a gable roof, vertical plank siding and no window openings.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 80003544, listed June 27, 1980. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence medium).
Key facts
| Address | N of Portersville on T 415, Slippery Rock Township, Princeton |
|---|---|
| County | Lawrence County |
| Listed | June 27, 1980 |
| Reference number | 80003544 |
| Resource type | Structure |
| Areas of significance | Engineering, Transportation |
| Level of significance | State |
| Status (as stated in the nomination) | Condition recorded as good. |
| Acreage | 0.1 |
| Coordinates | 40.95289, -80.17021 (NPS GIS) |
What listing means for this property
For a publicly owned building or structure, listing mainly matters when federal funds, permits or licences are involved: projects then go through Section 106 review so effects on the property are considered. Listing also strengthens applications for preservation grants and, for leased income-producing uses, can enable the federal rehabilitation tax credit.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 80003544.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q1915040
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.