Campbell's Bridge
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Why it's listed
Campbell's Bridge is a single-span concrete arch carrying Allentown Road over Unami Creek in Milford Township, Bucks County. Built in 1906, its segmental arch spans 72 feet and is carried on two thick ribs that are linked by transverse arches, which transfer the deck loads to the ribs. The open spandrels reduce the mass of the structure compared with earlier solid-filled barrel arches. Its builder is not recorded. The bridge is considered an early and very good example of the shift from solid barrel arches to ribbed open-spandrel arches in concrete, a decade of experimentation in the material. The surface of the arch is plain, without incised decoration, and the thin flat parapet rising to a gentle point recalls earlier camelback stone bridges. The bridge is the earliest of fifteen open-spandrel arches included in the group nomination. Its engineering significance rests on this place in the development of concrete arch design in Pennsylvania.
Significance in brief: The nomination argues the bridge is an important early example of the open-spandrel arch form in concrete. It is described as a very good example of the transition from solid filled barrel arches to ribbed open-spandrel arches. It is the earliest of fifteen open-spandrel arches included in the group nomination, and its thin parapet is said to recall older camelback stone arch bridges. The area of significance is engineering.
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 88000733, listed June 22, 1988. Summary generated October 2026 (model claude-haiku-5-5, prompt v1.1-2026-10-29, confidence medium).
Key facts
| Address | Allentown Rd. over Unami Creek, Milford Square |
|---|---|
| County | Bucks County |
| Listed | June 22, 1988 |
| Reference number | 88000733 |
| Resource type | Structure |
| Period of significance | 1906 |
| Criteria |
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| Areas of significance | Engineering |
| Level of significance | State |
| Status (as stated in the nomination) | Unaltered, with the vehicular use continuing at present according to the form. |
| Acreage | 0.9 |
| Coordinates | 40.42857, -75.39785 (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 88000733.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q5027957
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.