Ponakin Bridge
Why it's listed
Ponakin Road crosses the north branch of the Nashua River in Lancaster on a single-span iron Post through truss bridge built in 1871. It spans 100 feet, is 20 feet wide, has eight panels, and rests on granite block abutments. The town hired Watson Manufacturing Company, builders from Paterson, New Jersey, to replace the last of a series of wooden bridges on the site dating to the seventeenth century. The cost was $5,981, and the design followed the patent of civil engineer Simeon S. Post. The bridge once lay on the main route from Lancaster to Lunenburg but now sits on a quiet country road near a 1965 by-pass. It is notable as the only pure example of a Post truss known to the Historic American Engineering Record, and it forms a rare pair with the nearby Atherton Bridge. Town-funded repairs have kept it open to light traffic, with a four-ton limit.
Significance in brief: The nomination argues the bridge retains integrity of location, design, setting, materials and workmanship and is tied to major transportation routes and the development of Lancaster. It is described as the only remaining pure version of a Post truss known to the Historic American Engineering Record. With the nearby Atherton Bridge, it forms a unique pair of surviving examples in the country.
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 79000378, listed September 10, 1979. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence high).
Key facts
| Address | N of Lancaster on Ponakin Rd., Lancaster |
|---|---|
| County | Worcester County |
| Listed | September 10, 1979 |
| Reference number | 79000378 |
| Resource type | Structure |
| Period of significance | 1871 |
| Architect / builder | Watson Manufacturing Company |
| Architectural style | Post through truss |
| Areas of significance | Engineering, Transportation |
| Level of significance | National |
| Status (as stated in the nomination) | Town-owned and in use for automobile traffic, with a four-ton load limit that excludes trucks and heavy loads; condition listed as good. |
| Acreage | 0.3 |
| Coordinates | 42.48123, -71.68523 (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 79000378.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q7227555
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.