U.S. Customhouse
Why it's listed
Built in 1858 on West Oneida Street, one block west of the Oswego River, this limestone customhouse served the port of Oswego on Lake Ontario. It has three stories, a raised limestone basement, rusticated first-story walls, round-arched windows, and a projecting arcaded entrance pavilion on the north side. Two-story wings matching the original walls were added in 1935. Ammi B. Young, then Supervisory Architect of the U.S. Treasury, designed it with cast-iron columns and staircases as a fireproofing measure. The building is regarded as one of the finest surviving examples of his work and retains much of its original fabric. The customhouse regulated trade in salt, grain, and timber between Oswego, Canada, and the expanding West. Oswego's shipping importance declined after the Civil War but later revived with the St. Lawrence Seaway. The building continues to serve as the city's main post office and federal building.
Significance in brief: The customhouse played a significant role in the development of the port of Oswego and maritime commerce on Lake Ontario, regulating traffic in salt, grain, and timber between Oswego, Canada, and the West. It is an early "fireproof" building with a cast-iron structural system by Ammi B. Young, Supervisory Architect of the U.S. Treasury. It is considered among the finest surviving examples of his work.
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 76001262, listed November 21, 1976. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence high).
Key facts
| Address | W. Oneida St. between 1st and 2nd Sts., Oswego |
|---|---|
| County | Oswego County |
| Listed | November 21, 1976 |
| Reference number | 76001262 |
| Resource type | Building |
| Period of significance | 1858 |
| Architect / builder | Ammi B. Young (1798-1874) |
| Architectural style | Neo-classical; Italianate, Renaissance Revival north Italian mode |
| Areas of significance | Commerce, Politics/Government, Architecture |
| Level of significance | State |
| Status (as stated in the nomination) | Occupied and still in use as Oswego's main post office and federal office space; the form lists condition as altered, with an elevator and loading dock added in the twentieth century and the interior partitioned. |
| Acreage | 0.9 |
| Coordinates | 43.45482, -76.51090 (NPS GIS) |
What listing means for this property
National Register listing is honorary: it recognises significance and does not restrict what a private owner may do without federal money or permits. It unlocks the 20% federal rehabilitation tax credit for income-producing buildings, state credits in many states, and Section 106 review when federal agencies are involved. See what listing means in practice.
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 76001262.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q7889710
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.