Thompson Mill Covered Bridge
Why it's listed
Spanning the Kaskaskia River just north of Cowden in Shelby County, Illinois, this wooden covered bridge carries traffic on a township road. Its main span uses a Howe truss, with vertical iron tension rods and crossed wooden diagonals, and measures 103 feet 4 inches between piers, with steel I-beam approach spans at each end. The piers are tubular iron shells filled with shale. The form says the bridge was fabricated in Michigan, shipped to Shelbyville and hauled to the site by horse-drawn wagon, and it is named for the nearby Thompson Mill, a corn and saw mill that operated until 1914. The road once linked Springfield, Taylorville and Effingham and served local farms. At just 10 feet 7 inches wide, it is the narrowest of the eight 19th-century covered bridges left in Illinois. Its original timbers remain, and the roof and siding have been repaired several times, most recently in the 1960s. A state historical marker was dedicated in 1972.
Significance in brief: The nomination argues it is significant for its type of structure, its age and its continuous use. It is one of only eight remaining 19th-century covered bridges in Illinois and the narrowest of them. It also reflects 19th-century horse-and-buggy road construction and the nearby Thompson Mill.
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 75000675, listed March 13, 1975. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | 0.5 mi. NE of Cowden over Kaskaskia River, Cowden |
|---|---|
| County | Shelby County |
| Listed | March 13, 1975 |
| Reference number | 75000675 |
| Resource type | Structure |
| Period of significance | 19th Century (specific date given as about 1857) |
| Architectural style | Howe truss covered bridge; frame construction with vertical siding |
| Areas of significance | Engineering, Transportation |
| Level of significance | State, Local |
| Status (as stated in the nomination) | Excellent condition, unaltered, on its original site; still used by vehicular traffic on a township road. Roof and siding restored, with railings and approach beams altered in 1973 to restore the original appearance. |
| Acreage | 0.5 |
| Coordinates | 39.25837, -88.81812 (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 75000675.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q16901614
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.