Lock and Dam No. 15 Historic District
Why it's listed
Lock and Dam No. 15 crosses the Upper Mississippi River at the foot of the Rock Island Rapids, linking Arsenal Island in Illinois with the Iowa shore. The 359-acre district contains two navigation locks, each with a 16-foot lift, a dam of eleven roller gates, a hydroelectric power house, a storage house, an Iowa-side seawall and intercepting sewer, and the double-deck Rock Island Arsenal Bridge. Contractors built most of the complex between 1931 and 1934, and it went into service on March 7, 1934. The bridge dates to 1895-1896 and its swing span pier is encased in the wall between the locks. The complex is unusual because it had a completed auxiliary lock, as only two other complexes in the project did. A major rehabilitation in 1993 resurfaced the structures and replaced much machinery in kind, but the district retains its location, design, setting, and overall character. It remains in continuous use as part of the 9-Foot Navigation Project.
Significance in brief: The district is part of the Upper Mississippi River 9-Foot Navigation Project and began operating on March 7, 1934. It is one of only three complexes in the project built with a completed, operable auxiliary lock. It also incorporates the 1895-1896 Rock Island Arsenal Bridge, whose swing span pier is encased in the lock wall.
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 04000175, listed March 10, 2004. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | NW of Rodman Ave., Twd., NW tip Arsenal Island, Rock Island |
|---|---|
| County | Rock Island County |
| Listed | March 10, 2004 |
| Reference number | 04000175 |
| Resource type | District |
| Architect / builder | Contractors: Merritt-Chapman and Whitney Corporation (locks), Collier Construction Company (machinery and electrical system), S. A. Healy Company (dam and power house), McKeown Brothers Company (storage house), Steven A. Healy (Iowa seawall and sewer); contract drawings signed by Lenvick Ylvisaker of the UMVD |
| Architectural style | OTHER: lock and dam; OTHER: Pratt truss; OTHER: Baltimore truss; OTHER: camelback trough-truss; NO STYLE: power house |
| Areas of significance | Transportation, Engineering, Maritime History, Social History, Commerce, Conservation, Economics, Military, Politics/Government |
| Level of significance | National |
| Status (as stated in the nomination) | In continuous use since March 7, 1934; the locks and dam underwent a major rehabilitation in 1993 and are described as in excellent condition, though not all original architectural details survive. |
| Acreage | 359 |
| Within district | Rock Island Arsenal |
| Coordinates | 41.51799, -90.56431 (NPS GIS) |
What listing means for this property
This is a historic district. Buildings within its boundary are either contributing (they add to the district's significance) or non-contributing. Owners of contributing income-producing buildings can claim the 20% federal rehabilitation tax credit; homeowners should look at state credits. National Register districts impose no design review by themselves; a local historic district ordinance, if one exists, does (the difference explained).
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 04000175.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q1867483
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.