State Highway 9 Bridge at the Llano River
Also known as: Ms0071-04-018
Why it's listed
Carrying southbound US 87 over the Llano River southeast of Mason, this 902-foot bridge combines two 180-foot steel truss spans with concrete girder and steel I-beam approach spans. It was rebuilt in 1935-1936 after a June 1935 flood washed out the two truss spans and center pier of a 1930 bridge. Federal reviewers insisted the structure be raised to clear future high water. Texas Highway Department engineers responded with custom-designed Warren trusses whose floor beams sit flush with the bottom chord, raising the low steel while limiting how far the roadway had to rise. The form identifies it as the only Warren polygonal-chord truss bridge on a state highway in Texas, and its rarity of type underlies its engineering significance. Froemming Bros. of Austin built it, and Pittsburgh-Des Moines Steel fabricated the trusses. A concrete beam bridge added in 1971-1972 now handles northbound traffic, which has allowed the truss bridge to remain in service.
Significance in brief: The bridge is significant under Criterion C in the area of Engineering at the state level because of its rarity of type. Texas Highway Department engineers custom-designed its Warren polygonal-chord trusses after a 1935 flood destroyed the original spans. It is described as the only Warren polygonal-chord truss bridge on a state highway in Texas.
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 96001128, listed October 10, 1996. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence high).
Key facts
| Address | US 87, 10 mi. S of TX 29, Mason |
|---|---|
| County | Mason County |
| Listed | October 10, 1996 |
| Reference number | 96001128 |
| Resource type | Structure |
| Period of significance | 1936 |
| Architect / builder | Bridge Designer: Texas Highway Department; Truss Fabricator: Pittsburgh-Des Moines Steel Company of Des Moines, Iowa; Bridge Builder: Froemming Bros., Inc. of Austin, Texas |
| Architectural style | Other: Warren polygonal-chord through truss bridge |
| Criteria |
|
| Areas of significance | Engineering |
| Level of significance | State |
| Status (as stated in the nomination) | Remains in place serving southbound vehicular traffic on US 87; a companion bridge for northbound lanes was added in 1971-1972. |
| Acreage | 0.9 |
| Coordinates | 30.66122, -99.10972 (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 96001128.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q110001274
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.