Mountain Quarries Bridge
Also known as: Mountain Quarry Cement Bridge; American River Quarry Bridge; Pacific Portland Cement Company Railroad Bridge
Approximate location: the National Park Service places this pin arbitrarily within the property, not at a surveyed point (stated accuracy ±12 m).
Why it's listed
Spanning the American River just below the meeting of its North and Middle Forks near Auburn, this reinforced concrete railroad bridge was built between 1910 and 1912 for the Mountain Quarries Company, a subsidiary of Pacific Portland Cement Company. It carries a single track on three 140-foot skewed arches, stands 70 feet high, and measures about 650 feet including its approaches. Engineer John B. Leonard designed it to bear heavy Mallet locomotives hauling limestone from the quarry to the rail line at Auburn. Its skewed piers answer the narrow, steep canyon, and it cost about twenty percent less than a comparable steel structure. The bridge was listed for its engineering under Criterion C, as an early and rare use of reinforced concrete in railroading. It withstood floods that destroyed newer highway bridges upstream and served as a vehicle detour in 1964-65. Rail use ended around 1940, and today hikers and riders cross it on a recreation trail.
Significance in brief: The nomination argues the bridge meets Criterion C for distinctive engineering, as an early and rare use of reinforced concrete in a railroad bridge and the work of engineer John B. Leonard. It was designed to carry heavy Mallet locomotives across a restricted, skewed canyon site. It has survived major floods that destroyed newer bridges upstream.
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 04000014, listed February 11, 2004. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | North Fork of the American River, Auburn |
|---|---|
| County | Placer County |
| Listed | February 11, 2004 |
| Reference number | 04000014 |
| Resource type | Structure |
| Period of significance | 1912 |
| Architect / builder | Mr. John B. Leonard, of the firm Leonard & Day, Engineer; Duncanson-Harrelson Company, Building Contractors; J.B. Harrington, Chief Construction Engineer |
| Architectural style | Other - Concrete Arch Bridge |
| Criteria |
|
| Areas of significance | Engineering |
| Level of significance | State |
| Status (as stated in the nomination) | Rail service ended around 1939-1940 and the tracks were removed; the bridge is now used by pedestrians and equestrians. A pier foundation was stabilized and repaired in the late 1990s. |
| Acreage | 0.9 |
| Coordinates | 38.91258, -121.04146 (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 04000014.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q14683436
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.