I Street Bridge
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Why it's listed
Spanning the Sacramento River between Sacramento and Yolo Counties, this double-deck steel truss bridge carries State Highway 16 on its concrete upper deck and the Southern Pacific's double-track main line below. Completed in 1911, it replaced a single-track timber Howe truss swing bridge in use since the 1860s that had become a bottleneck on the railroad's main line. Construction began in June 1910 under an agreement between the railroad and the two counties. The bridge has 33 spans totaling 2,194 feet. Its center-bearing swing span weighs about 6,300,000 pounds and was the heaviest in the world when built; it is still the heaviest in the United States. American Bridge Company supplied the roughly 4,500 tons of steel, and John D. Isaacs directed the design. New approaches built in 1937 and 1959 slightly affected its design integrity, but the bridge remains a substantial reminder of the Harriman-era improvements to the Southern Pacific.
Significance in brief: The nomination argues the bridge is a substantial reminder of the Southern Pacific improvements made under E.H. Harriman. Its center-bearing swing span was the heaviest in the world when built and remains the heaviest in the U.S. It represents a bridge type, an early twentieth century period, and shop-fabricated, field-riveted steel truss construction.
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 82002233, listed April 22, 1982. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | CA 16, Sacramento |
|---|---|
| County | Sacramento County |
| Listed | April 22, 1982 |
| Reference number | 82002233 |
| Resource type | Structure |
| Period of significance | 1900- |
| Architect / builder | Southern Pacific/American Bridge Co.; designed under Southern Pacific consulting engineer John D. Isaacs |
| Areas of significance | Engineering, Transportation |
| Level of significance | Local |
| Status (as stated in the nomination) | Listed as occupied, in excellent condition and altered; it still carries Southern Pacific main line tracks on the lower deck and State Highway 16 on the upper deck. Approaches were rebuilt in 1937 and 1959. |
| Acreage | 0.9 |
| Coordinates | 38.57736, -121.50616 (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 82002233.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q5979075
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.