Allegheny River Lock and Dam No. 3
Also known as: New Lock No. 3
Why it's listed
Located about 14.5 miles upstream from the mouth of the Allegheny River near New Kensington, Pennsylvania, this lock and dam was built by the U.S. Army Corps of Engineers in 1932-1934 to replace an older lock whose chamber, at 289 by 56 feet, had become too small for four-barge tows. The new lock chamber measures 56 by 360 feet and lifts boats 13.8 feet. The complex includes a reinforced concrete lock, a dam about 1,435 feet long, an esplanade, a two-story operations building with a flat rubber roof, and a gauging station. Vang Construction Company built the lock and operations building, and Seeds and Derham built the dam. The facility formed part of a slackwater system that gave commercial barges access to the river upstream and to the steel mills and aluminum plant in the New Kensington area. Its original design, layout and much of its machinery remain in place, which the nomination cites as the basis for its significance as a representative example of lock and dam construction from that period.
Significance in brief: The nomination argues the lock and dam are significant for their role in the Allegheny River slackwater navigation system, which allowed barge and towboat access to industrial centers including New Kensington's aluminum plant. It also argues the 1932-1934 lock and dam is a representative example of its type and retains much of its original design and equipment.
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 00000397, listed April 21, 2000. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence high).
Key facts
| Address | Approx. 1 mi. N of Barrington, New Kensington |
|---|---|
| County | Allegheny County |
| Listed | April 21, 2000 |
| Reference number | 00000397 |
| Resource type | Structure |
| Period of significance | 1903-1948 |
| Architect / builder | Locks - Vang Construction Co.; Dam - Seeds & Derham |
| Architectural style | Late Nineteenth and Early Twentieth Century Revival |
| Criteria |
|
| Areas of significance | Transportation, Maritime History, Architecture, Engineering |
| Level of significance | State |
| Status (as stated in the nomination) | Operating lock and dam; the old Lock 3 land wall remains and is used as a marina, and the locktenders' house is no longer owned by the Corps of Engineers. |
| Acreage | 10.6 |
| Coordinates | 40.53989, -79.81117 (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 00000397.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q4731335
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.